V4L/DVB: videobuf: Remove the videobuf_sg_dma_map/unmap functions

Instead of creating dirty wrappers around videobuf_dma_map/unmap that
create a dummy videobuf_queue structure, modify videobuf_dma_map/unmap
to take a device pointer argument and use it directly. The
videobuf_sg_dma_map/unmap then become unused and can be removed.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>