[media] cx231xx: create DVB graph

cx231xx is simple with regards to DVB: all boards have just one
DVB adapter. So, we can use the default DVB helper function to
create the DVB media graph.

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

diff --cc drivers/media/usb/cx231xx/cx231xx-dvb.c
Simple merge