Add a check to make sure the input interface (CSI-2 or parallel) allow
for the requested input bus format. If not inform the user and error out
rather then try to continue with incorrect settings.

While at it add the missing define for RGB666 that is not yet supported
in the driver but we can preemptively check for it in this context
already.
Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>