[media] add DTMB support for DVB API

Cc: Patrick Boettcher <pboettcher@kernellabs.com>
Cc: Andreas Oberritter <obi@linuxtv.org>
Cc: Mauro Carvalho Chehab <mchehab@redhat.com>
Acked-by: Patrick Boettcher <pboettcher@kernellabs.com>
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>