media: vivid: add vertical down sampling to imagesize calc

To correctly set the size of the image in a plane, it's needed
to divide the height of image by the vertical down sampling factor.
This was only happening in vivid_try_fmt_vid_cap(), but now it
applied in others sizeimage calculations as well.

Signed-off-by: André Almeida <andre.almeida@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>