OMAPDSS: DISPC: Add dispc_mgr_get_vsync_irq()

Add dispc_mgr_get_vsync_irq() which returns the irq number for vsync on
the given channel.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
diff --git a/drivers/video/omap2/dss/dss.h b/drivers/video/omap2/dss/dss.h
index 03c7244..1535496 100644
--- a/drivers/video/omap2/dss/dss.h
+++ b/drivers/video/omap2/dss/dss.h
@@ -409,9 +409,9 @@
 void dispc_ovl_set_channel_out(enum omap_plane plane,
 		enum omap_channel channel);
 
-
 void dispc_mgr_enable_fifohandcheck(enum omap_channel channel, bool enable);
 void dispc_mgr_set_lcd_size(enum omap_channel channel, u16 width, u16 height);
+u32 dispc_mgr_get_vsync_irq(enum omap_channel channel);
 bool dispc_mgr_go_busy(enum omap_channel channel);
 void dispc_mgr_go(enum omap_channel channel);
 bool dispc_mgr_is_enabled(enum omap_channel channel);