V4L/DVB (5994): ivtv: make VIDIOC_INT_RESET support smarter.

Add support to optionally reset the IR and/or the video digitizer.

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