drm/bridge: adv7511: 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/20180424131450.1910-1-luc.vanoostenryck@gmail.com

drivers/gpu/drm/bridge/adv7511/adv7511_drv.c

@@ -654,7 +654,7 @@ adv7511_detect(struct adv7511 *adv7511, struct drm_connector *connector)
 	return status;
 }
 
-static int adv7511_mode_valid(struct adv7511 *adv7511,
+static enum drm_mode_status adv7511_mode_valid(struct adv7511 *adv7511,
 			      struct drm_display_mode *mode)
 {
 	if (mode->clock > 165000)