drm/bridge: panel: export drm_panel_bridge_connector

The function was unexported and was causing link failures for pl111 (and
probably the other user tve200) in a module build.

Fixes: d383fb5f ("drm: get drm_bridge_panel connector via helper")
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Linux Walleij <linux.walleij@linaro.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mihail Atanassov <mihail.atanassov@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191210144834.27491-1-mihail.atanassov@arm.com

drivers/gpu/drm/bridge/panel.c

@@ -306,3 +306,4 @@ struct drm_connector *drm_panel_bridge_connector(struct drm_bridge *bridge)
 
 	return &panel_bridge->connector;
 }
+EXPORT_SYMBOL(drm_panel_bridge_connector);