[media] v4l2-ctrls: replace BUG_ON by WARN_ON

BUG_ON is unnecessarily strict.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

drivers/media/v4l2-core/v4l2-ctrls.c

@@ -1942,7 +1942,8 @@ void v4l2_ctrl_cluster(unsigned ncontrols, struct v4l2_ctrl **controls)
 	int i;
 
 	/* The first control is the master control and it must not be NULL */
-	BUG_ON(ncontrols == 0 || controls[0] == NULL);
+	if (WARN_ON(ncontrols == 0 || controls[0] == NULL))
+		return;
 
 	for (i = 0; i < ncontrols; i++) {
 		if (controls[i]) {