OMAPDSS: APPLY: Constify timings argument in dss_mgr_set_timings

The function dss_mgr_set_timings is supposed to apply timings passed by an
interface driver. It is not supposed to change the timings. Add const qualifier
to the omap_video_timings pointer argument in dss_mgr_set_timings().

Signed-off-by: Archit Taneja <archit@ti.com>
diff --git a/drivers/video/omap2/dss/dss.h b/drivers/video/omap2/dss/dss.h
index f67afe7..3682e3f 100644
--- a/drivers/video/omap2/dss/dss.h
+++ b/drivers/video/omap2/dss/dss.h
@@ -206,7 +206,7 @@
 		struct omap_dss_device *dssdev);
 int dss_mgr_unset_device(struct omap_overlay_manager *mgr);
 void dss_mgr_set_timings(struct omap_overlay_manager *mgr,
-		struct omap_video_timings *timings);
+		const struct omap_video_timings *timings);
 void dss_mgr_set_lcd_config(struct omap_overlay_manager *mgr,
 		const struct dss_lcd_mgr_config *config);
 const struct omap_video_timings *dss_mgr_get_timings(struct omap_overlay_manager *mgr);