[media] Properly implement ITU-T J.88 Annex C support

The Annex C support were broken with the previous implementation,
as, at xc5000 and tda18271c2dd, it were choosing the wrong bandwidth
for some symbol rates.

At DRX-J, it were always selecting Annex A, even having Annex C
support coded there.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>