[media] cx231xx: fix compilation if the media controller is not defined

drivers/media/usb/cx231xx/cx231xx-cards.c: In function ‘cx231xx_usb_probe’:
drivers/media/usb/cx231xx/cx231xx-cards.c:1589:15: error: ‘struct v4l2_device’ has no member named ‘mdev’
  dev->v4l2_dev.mdev = dev->media_dev;
               ^
drivers/media/usb/cx231xx/cx231xx-cards.c:1589:26: error: ‘struct cx231xx’ has no member named ‘media_dev’
  dev->v4l2_dev.mdev = dev->media_dev;
                          ^
scripts/Makefile.build:257: recipe for target 'drivers/media/usb/cx231xx/cx231xx-cards.o' failed

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

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

@@ -1586,7 +1586,9 @@ static int cx231xx_usb_probe(struct usb_interface *interface,
 	cx231xx_media_device_register(dev, udev);
 
 	/* Create v4l2 device */
+#ifdef CONFIG_MEDIA_CONTROLLER
 	dev->v4l2_dev.mdev = dev->media_dev;
+#endif
 	retval = v4l2_device_register(&interface->dev, &dev->v4l2_dev);
 	if (retval) {
 		dev_err(d, "v4l2_device_register failed\n");

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

@@ -540,7 +540,9 @@ static int register_dvb(struct cx231xx_dvb *dvb,
 
 	/* register network adapter */
 	dvb_net_init(&dvb->adapter, &dvb->net, &dvb->demux.dmx);
+#ifdef CONFIG_MEDIA_CONTROLLER_DVB
 	dvb_create_media_graph(dev->media_dev);
+#endif
 	return 0;
 
 fail_fe_conn: