V4L/DVB (5732): Add ivtv CROPCAP support and fix ivtv S_CROP for video output.

The VIDIOC_CROPCAP ioctl was missing in ivtv.
The handling of output video cropping was wrong. This has now been fixed.

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