Add the demod and tuner dependencies required for the Avermedia m780 to the
Kconfig for the ngene driver.

Thanks to Oliver Endriss for pointing this out.
Signed-off-by: Devin Heitmueller <dheitmueller@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>