V4L/DVB: cx88: improve error handling

Return -EINVAL if we don't find the right query control id.
Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/cx88/cx88-video.c

@@ -1538,9 +1538,12 @@ static int radio_queryctrl (struct file *file, void *priv,
 		c->id >= V4L2_CID_LASTP1)
 		return -EINVAL;
 	if (c->id == V4L2_CID_AUDIO_MUTE) {
-		for (i = 0; i < CX8800_CTLS; i++)
+		for (i = 0; i < CX8800_CTLS; i++) {
 			if (cx8800_ctls[i].v.id == c->id)
 				break;
+		}
+		if (i == CX8800_CTLS)
+			return -EINVAL;
 		*c = cx8800_ctls[i].v;
 	} else
 		*c = no_ctl;