V4L/DVB (10486): ivtv/cx18: fix g_fmt and try_fmt for raw video

The raw video device didn't report the image size correctly.

When setting a new image the image height has to be a multiple of 32 lines.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>