[media] media-device: supress backlinks at G_TOPOLOGY ioctl

Due to the graph traversal algorithm currently in usage, we
need a copy of all data links. Those backlinks should not be
send to userspace, as otherwise, all links there will be
duplicated.

Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/media-device.c

@@ -333,6 +333,9 @@ static long __media_device_get_topology(struct media_device *mdev,
 	/* Get links and number of links */
 	i = 0;
 	media_device_for_each_link(link, mdev) {
+		if (link->is_backlink)
+			continue;
+
 		i++;
 
 		if (ret || !topo->links)