Completely rely on the video_ioctl2 debugging facilities rather than
doing it ourselves.

Fill in some missing fields in ivtv with VIDIOC_G_FBUF.
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>