media: fsl-viu: deprecate this driver

Deprecate the fsl-viu driver. This driver does not use the vb2 framework
for video streaming, instead it uses the old videobuf framework.

We want to get rid of these old drivers, so deprecated it for future
removal.

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