[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>
diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c
index d9d42fa..246d7e6 100644
--- a/drivers/media/media-entity.c
+++ b/drivers/media/media-entity.c
@@ -625,6 +625,7 @@
 	backlink->source = &source->pads[source_pad];
 	backlink->sink = &sink->pads[sink_pad];
 	backlink->flags = flags;
+	backlink->is_backlink = true;
 
 	/* Initialize graph object embedded at the new link */
 	media_gobj_init(sink->graph_obj.mdev, MEDIA_GRAPH_LINK,