drm: Check for connection_mutex in drm_select_eld

drm_select_eld should check for mode_config.connection_mutex as
well as mode_config.mutex: We need that since this function checks
conector->encoder links.
Signed-off-by: NSean Paul <seanpaul@chromium.org>
[danvet: Pimp commit message slightly.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/drm_edid.c

@@ -3305,6 +3305,7 @@ struct drm_connector *drm_select_eld(struct drm_encoder *encoder,
 	struct drm_device *dev = encoder->dev;
 
 	WARN_ON(!mutex_is_locked(&dev->mode_config.mutex));
+	WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));
 
 	list_for_each_entry(connector, &dev->mode_config.connector_list, head)
 		if (connector->encoder == encoder && connector->eld[0])