V4L/DVB (8783): v4l: add all missing video_device release callbacks

All drivers that call video_device_register where checked to see if they
set the release callback of struct video_device. Where that callback was
missing it was added.

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