[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: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/usb/cx231xx/cx231xx-dvb.c

@@ -540,6 +540,7 @@ static int register_dvb(struct cx231xx_dvb *dvb,
 
 	/* register network adapter */
 	dvb_net_init(&dvb->adapter, &dvb->net, &dvb->demux.dmx);
+	dvb_create_media_graph(dev->media_dev);
 	return 0;
 
 fail_fe_conn: