[media] videobuf2-core: move plane verification out of __fill_v4l2/vb_buffer

The plane verification should be done before actually queuing or
dequeuing buffers, so move it out of __fill_v4l2_buffer and __fill_vb_buffer
and call it as a separate step.
This also makes it possible to change the return type of __fill_v4l2/vb_buffer
to void.
The dqbuf case took some special care: before removing a buffer from the
done_list you have to verify that the receiving v4l2_buffer has enough room
for all the planes. The number of planes can differ between buffers due to the
fact that buffers for other formats can be prepared using VIDIOC_PREPARE_BUF.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Reviewed-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Tested-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>