[media] sh-vou: convert to vb2

This converts this driver to videobuf2. As usual it is a big and hard to review
patch, but this is always a big-bang change.

It has been tested with my Renesas board.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>