V4L/DVB (3430): Add new internal VIDIOC_INT commands

- Add new internal VIDIOC_INT commands for setting the tuner mode,
for putting a chip into standby mode and to set/get the routing
of inputs/outputs of audio or video of a chip. These new commands
will replace older commands that are no longer up to the task.

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