OMAPDSS: APPLY: track whether a manager is enabled

Add "enabled" field to struct omap_overlay_manager, which tells if the
output is enabled or not. This will be used in apply.c in the following
patches.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
diff --git a/include/video/omapdss.h b/include/video/omapdss.h
index 04741cd..d61efc3 100644
--- a/include/video/omapdss.h
+++ b/include/video/omapdss.h
@@ -432,6 +432,8 @@
 	struct omap_dss_device *device;
 	struct omap_overlay_manager_info info;
 
+	bool enabled;
+
 	bool device_changed;
 	/* if true, info has been changed but not applied() yet */
 	bool info_dirty;