OMAPDSS: DISPC: make dispc_ovl_set_channel_out() public

Make dispc_ovl_set_channel_out() public so that later patches can handle
changing overlay's manager.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
diff --git a/drivers/video/omap2/dss/dispc.c b/drivers/video/omap2/dss/dispc.c
index 5bbd838..5130f88 100644
--- a/drivers/video/omap2/dss/dispc.c
+++ b/drivers/video/omap2/dss/dispc.c
@@ -875,8 +875,7 @@
 	REG_FLD_MOD(DISPC_OVL_ATTRIBUTES(plane), m, 4, 1);
 }
 
-static void dispc_ovl_set_channel_out(enum omap_plane plane,
-		enum omap_channel channel)
+void dispc_ovl_set_channel_out(enum omap_plane plane, enum omap_channel channel)
 {
 	int shift;
 	u32 val;