drm/dp-mst: Missing kernel doc

Cc: Dave Airlie <airlied@redhat.com>
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1468612088-9721-7-git-send-email-daniel.vetter@ffwll.ch
diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 5020a2a..04e4571 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -2365,6 +2365,7 @@
 
 /**
  * drm_dp_mst_detect_port() - get connection status for an MST port
+ * @connector: DRM connector for this port
  * @mgr: manager for this port
  * @port: unverified pointer to a port
  *