V4L/DVB (12725): v4l: warn when desired devnodenr is in use & add _no_warn function

Warn when the desired device node number is already in use, except when
the new video_register_device_no_warn function is called since in some
use-cases that warning is not relevant.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/video/cx18/cx18-streams.c b/drivers/media/video/cx18/cx18-streams.c
index 6c988b9..7df513a2 100644
--- a/drivers/media/video/cx18/cx18-streams.c
+++ b/drivers/media/video/cx18/cx18-streams.c
@@ -245,7 +245,7 @@
 	video_set_drvdata(s->video_dev, s);
 
 	/* Register device. First try the desired minor, then any free one. */
-	ret = video_register_device(s->video_dev, vfl_type, num);
+	ret = video_register_device_no_warn(s->video_dev, vfl_type, num);
 	if (ret < 0) {
 		CX18_ERR("Couldn't register v4l2 device for %s (device node number %d)\n",
 			s->name, num);