[media] tda10021: Add support for DVB-C Annex C

While tda10021 supports both DVB-C Annex A and C, it is currently
hard-coded to Annex A. Add support for Annex C and re-work the
code in order to report the delivery systems, thans to Andreas,
that passed us the register settings for the Roll-off factor.

Thanks-to: Andreas Oberriter <obi@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>