[media] DVB: Use a unique delivery system identifier for DVBC_ANNEX_C

Use a unique delivery system identifier for DVBC_ANNEX_C, just like any
other.

DVBC_ANNEX_A and DVBC_ANNEX_C have slightly different parameters
and are used in 2 geographically different locations.

Signed-off-by: Manu Abraham <abraham.manu@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>