OMAPDSS: DISPC: make dispc_ovl_set_fifo_threshold() public

Make dispc_ovl_set_fifo_threshold() public so that later patches can
handle overlay fifo configuration.

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 5130f88..8249731 100644
--- a/drivers/video/omap2/dss/dispc.c
+++ b/drivers/video/omap2/dss/dispc.c
@@ -1056,8 +1056,7 @@
 	return dispc.fifo_size[plane];
 }
 
-static void dispc_ovl_set_fifo_threshold(enum omap_plane plane, u32 low,
-		u32 high)
+void dispc_ovl_set_fifo_threshold(enum omap_plane plane, u32 low, u32 high)
 {
 	u8 hi_start, hi_end, lo_start, lo_end;
 	u32 unit;