OMAP: DSS2: add detect() to omap_dss_driver struct

detect() can be used to probe if the display is connected.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

include/video/omapdss.h

@@ -624,6 +624,7 @@ struct omap_dss_driver {
 	u32 (*get_wss)(struct omap_dss_device *dssdev);
 
 	int (*read_edid)(struct omap_dss_device *dssdev, u8 *buf, int len);
+	bool (*detect)(struct omap_dss_device *dssdev);
 };
 
 int omap_dss_register_driver(struct omap_dss_driver *);