dmaengine: remove DMA_MEMCPY_SG once again

dmaengine: remove DMA_MEMCPY_SG once again

This was removed before due to the complete lack of users, but
3218910fd585 ("dmaengine: Add core function and capability check for
DMA_MEMCPY_SG") and 29cf37fa6dd9 ("dmaengine: Add consumer for the new
DMA_MEMCPY_SG API function.") added it back despite still not having
any users whatsoever.

Fixes: 3218910fd585 ("dmaengine: Add core function and capability check for DMA_MEMCPY_SG")
Fixes: 29cf37fa6dd9 ("dmaengine: Add consumer for the new DMA_MEMCPY_SG API function.")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/20220606074733.622616-1-hch@lst.de
Signed-off-by: Vinod Koul <vkoul@kernel.org>