DMA: Add option to configure psram block size

[seijikun]

In the current DMA abstraction, I miss the option to configure the PSRAM blocksize.
In esp-idf, this can be set to 3 possible values:

• #define GDMA_LL_EXT_MEM_BK_SIZE_16B (0)
• #define GDMA_LL_EXT_MEM_BK_SIZE_32B (1)
• #define GDMA_LL_EXT_MEM_BK_SIZE_64B (2)

This is the corresponding esp-idf method:

/**
 * @brief Set DMA TX channel memory block size
 * @param size_index Supported value: GDMA_LL_EXT_MEM_BK_SIZE_16B/32B/64B
 */
static inline void gdma_ll_tx_set_block_size_psram(gdma_dev_t *dev, uint32_t channel, uint32_t size_index)
{
    dev->channel[channel].out.conf1.out_ext_mem_bk_size = size_index;
}

I would've loved to add it myself, but after some time of looking at esp-hal's DMA abstraction, I had to capitulate to the architecture, sorry.

[Dominaezzz]

I'd argue this is largely solved by #2161 , even if all drivers don't support the buffer traits yet.

EDIT: Perhaps this can be superseded by #2269.