[media] v4l: VIDEOBUF2_DMA_SG should depend on HAS_DMA

If NO_DMA=y:

    ERROR: "dma_unmap_sg" [drivers/media/v4l2-core/videobuf2-dma-sg.ko] undefined!
    ERROR: "dma_map_sg" [drivers/media/v4l2-core/videobuf2-dma-sg.ko] undefined!
    ERROR: "dma_sync_sg_for_cpu" [drivers/media/v4l2-core/videobuf2-dma-sg.ko] undefined!

VIDEOBUF2_DMA_SG cannot be enabled manually by the user, it's always
selected automatically by drivers that need it. Several of those drivers
already have an explicit dependency on HAS_DMA.

Make VIDEOBUF2_DMA_SG depend on HAS_DMA. This makes it easier to find
drivers that select VIDEOBUF2_DMA_SG without depending on HAS_DMA, as
Kconfig will give a warning.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>