V4L/DVB (13553): v4l: Use the video_is_registered function in device drivers

Fix all device drivers to use the video_is_registered function instead
of checking video_device::minor.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/video/cx88/cx88-video.c b/drivers/media/video/cx88/cx88-video.c
index 55063a7..0259ac6 100644
--- a/drivers/media/video/cx88/cx88-video.c
+++ b/drivers/media/video/cx88/cx88-video.c
@@ -1778,21 +1778,21 @@
 static void cx8800_unregister_video(struct cx8800_dev *dev)
 {
 	if (dev->radio_dev) {
-		if (-1 != dev->radio_dev->minor)
+		if (video_is_registered(dev->radio_dev))
 			video_unregister_device(dev->radio_dev);
 		else
 			video_device_release(dev->radio_dev);
 		dev->radio_dev = NULL;
 	}
 	if (dev->vbi_dev) {
-		if (-1 != dev->vbi_dev->minor)
+		if (video_is_registered(dev->vbi_dev))
 			video_unregister_device(dev->vbi_dev);
 		else
 			video_device_release(dev->vbi_dev);
 		dev->vbi_dev = NULL;
 	}
 	if (dev->video_dev) {
-		if (-1 != dev->video_dev->minor)
+		if (video_is_registered(dev->video_dev))
 			video_unregister_device(dev->video_dev);
 		else
 			video_device_release(dev->video_dev);