drm/bridge: tc358767: fix mode_valid's return type

The method struct drm_connector_helper_funcs::mode_valid is defined
as returning an 'enum drm_mode_status' but the driver implementation
for this method uses an 'int' for it.

Fix this by using 'enum drm_mode_status' in the driver too.
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20180424131453.1961-1-luc.vanoostenryck@gmail.com

drivers/gpu/drm/bridge/tc358767.c

@@ -1102,7 +1102,7 @@ static bool tc_bridge_mode_fixup(struct drm_bridge *bridge,
 	return true;
 }
 
-static int tc_connector_mode_valid(struct drm_connector *connector,
+static enum drm_mode_status tc_connector_mode_valid(struct drm_connector *connector,
 				   struct drm_display_mode *mode)
 {
 	/* DPI interface clock limitation: upto 154 MHz */