V4L2: support for P010 (HDR) video format for UVC devices

[awawa-dev]

The V4L2_PIX_FMT_P010 format is defined in the Kernel API, but unfortunately V4L2 ignores UVC capture devices offering this format, resulting in this error in dmesg:

Unknown video format 30313050-0000-0010-8000-00aa00389b71

This PR adds support for V4L2_PIX_FMT_P010 to V4L2. The P010 video format is used in the latest generation of video grabbers to capture HDR10 signal. Tested with Elgato HD60X on RPi 5 with v4l2-ctl and HyperHDR.

pi@rpi5:~ $ v4l2-ctl --list-formats-ext
ioctl: VIDIOC_ENUM_FMT
        Type: Video Capture

        [0]: 'YUYV' (YUYV 4:2:2)
                Size: Discrete 1920x1080
                        Interval: Discrete 0.017s (60.000 fps)
                        Interval: Discrete 0.020s (50.000 fps)
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                Size: Discrete 1600x1200
                        Interval: Discrete 0.017s (60.000 fps)
                        Interval: Discrete 0.020s (50.000 fps)
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                Size: Discrete 1280x720
                        Interval: Discrete 0.017s (60.000 fps)
                        Interval: Discrete 0.020s (50.000 fps)
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                Size: Discrete 720x576
                        Interval: Discrete 0.017s (60.000 fps)
                        Interval: Discrete 0.020s (50.000 fps)
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                Size: Discrete 720x480
                        Interval: Discrete 0.017s (60.000 fps)
                        Interval: Discrete 0.020s (50.000 fps)
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                Size: Discrete 640x480
                        Interval: Discrete 0.017s (60.000 fps)
                        Interval: Discrete 0.020s (50.000 fps)
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
        [1]: 'NV12' (Y/UV 4:2:0)
                Size: Discrete 3840x2160
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                Size: Discrete 2560x1440
                        Interval: Discrete 0.017s (60.000 fps)
                        Interval: Discrete 0.020s (50.000 fps)
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                Size: Discrete 1920x1080
                        Interval: Discrete 0.008s (120.000 fps)
                        Interval: Discrete 0.017s (60.000 fps)
                        Interval: Discrete 0.020s (50.000 fps)
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                Size: Discrete 1600x1200
                        Interval: Discrete 0.017s (60.000 fps)
                        Interval: Discrete 0.020s (50.000 fps)
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                Size: Discrete 1280x720
                        Interval: Discrete 0.017s (60.000 fps)
                        Interval: Discrete 0.020s (50.000 fps)
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                Size: Discrete 720x576
                        Interval: Discrete 0.017s (60.000 fps)
                        Interval: Discrete 0.020s (50.000 fps)
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                Size: Discrete 720x480
                        Interval: Discrete 0.017s (60.000 fps)
                        Interval: Discrete 0.020s (50.000 fps)
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                Size: Discrete 640x480
                        Interval: Discrete 0.017s (60.000 fps)
                        Interval: Discrete 0.020s (50.000 fps)
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
        [2]: 'P010' (10-bit Y/UV 4:2:0)
                Size: Discrete 1920x1080
                        Interval: Discrete 0.017s (60.000 fps)
                        Interval: Discrete 0.020s (50.000 fps)
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                Size: Discrete 1280x720
                        Interval: Discrete 0.017s (60.000 fps)
                        Interval: Discrete 0.020s (50.000 fps)
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)

[6by9]

This patch needs to go upstream as we don't have any downstream patches for UVC.
We are happy to backport patches from later upstream releases where they are useful.