V4L/DVB (13944): vivi: Fix test of unsigned in vivi_create_instance()

video_nr is unsigned so the test did not work.
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/vivi.c

@@ -1371,7 +1371,7 @@ static int __init vivi_create_instance(int inst)
 	/* Now that everything is fine, let's add it to device list */
 	list_add_tail(&dev->vivi_devlist, &vivi_devlist);
 
-	if (video_nr >= 0)
+	if (video_nr != -1)
 		video_nr++;
 
 	dev->vfd = vfd;