V4L/DVB (9229): cx88: Add intial config for FM radio support

This add initial configuration for radio support on the
hvr-3000/4000. FM radio doesn't work as yet without
further patches (to come), but this prepares for
that.

Experimental radio support shows that it works
when combined with additional audio routing
work for cards with an FMD1216ME analogue
frontend, but not the MEX variant (more later).

Signed-off-by: Darron Broad <darron@kewl.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>