OMAPDSS: DISPC: make _enable_mgr_out public as "dispc_mgr_enable"

We need a low level manager-enable function for omapdrm. We have that
function as dispc internal func, _enable_mgr_out().

This patch exposes that function, and renames it to dispc_mgr_enable().

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 687eddf..85c6fc8 100644
--- a/drivers/video/omap2/dss/dss.h
+++ b/drivers/video/omap2/dss/dss.h
@@ -435,6 +435,7 @@
 u32 dispc_mgr_get_sync_lost_irq(enum omap_channel channel);
 bool dispc_mgr_go_busy(enum omap_channel channel);
 void dispc_mgr_go(enum omap_channel channel);
+void dispc_mgr_enable(enum omap_channel channel, bool enable);
 bool dispc_mgr_is_enabled(enum omap_channel channel);
 void dispc_mgr_enable_sync(enum omap_channel channel);
 void dispc_mgr_disable_sync(enum omap_channel channel);