V4L/DVB (3711): Add support for VIDIOC_INT_S_CRYSTAL_FREQ internal command.

Some saa7115-based cards use a different crystal frequency and a different
audio clock generation. Add a new VIDIOC_INT_S_CRYSTAL_FREQ command to be
able to set these values.
Also change the default APLL setting to 0. It makes no sense to have the
audio clock independent from the video clock, this can lead to audio/video
synchronization problems. Setting this to 0 is also consistent with the old
saa7114.c source and the way the Hauppauge Windows driver sets it.

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