[nano]: rollback-altboot failed between 2.56.0+rev1 and 2.67.3+rev2

[acostach]

Although u-boot loads the right kernel and dtb that correspond to the 2.56.0+rev1 from the previous rootfs, that old kernel doesn't boot anymore and resets continuously with no logs, even on development images. So the contents in one or more raw partitions, that is new, can't be handled by the previous kernel. Happens both on the sd and emmc variants.