Request demodulator auto-detect transmission parameters in case of
garbage parameters provided by application for compatibility.
That's needed at least for MPlayer compatibility currently.

Thanks to Jelle de Jong for reporting issue and providing SSH access to
Devin for debugging.

Thanks to Devin Heitmueller for hard debug work he did to find that bug.

Cc: Devin Heitmueller <dheitmueller@kernellabs.com>
Cc: Jelle de Jong <jelledejong@powercraft.nl>
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>