[media] tda18271c2dd: fix support for DVB-C

As reported by Hartmut <e9hack@googlemail.com>:

> A break is missing before the default statement. Delivery systems for DVB-C result always
> in an error.

Reported-by: Hartmut <e9hack@googlemail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>