Most if not all codecs will need to implement these ioctls and
it is expected to be the same for all codecs. So add this to
the core v4l2-mem2mem framework so that this code can easily be
reused.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>