drm/omap: Add dispc_mgr_get_supported_outputs()

We are removing the use of the 'struct omap_overlay_manager' from
omapdrm, and one part of that is removing the use of
mgr->supported_outputs field.

This patch adds dispc_mgr_get_supported_outputs() function which can be
used instead of mgr->supported_outputs. omap_crtc.c is changed to use
the new function.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
diff --git a/drivers/gpu/drm/omapdrm/dss/dispc.c b/drivers/gpu/drm/omapdrm/dss/dispc.c
index a4274dc..a594089 100644
--- a/drivers/gpu/drm/omapdrm/dss/dispc.c
+++ b/drivers/gpu/drm/omapdrm/dss/dispc.c
@@ -2910,6 +2910,12 @@
 }
 EXPORT_SYMBOL(dispc_ovl_enabled);
 
+enum omap_dss_output_id dispc_mgr_get_supported_outputs(enum omap_channel channel)
+{
+	return dss_feat_get_supported_outputs(channel);
+}
+EXPORT_SYMBOL(dispc_mgr_get_supported_outputs);
+
 void dispc_mgr_enable(enum omap_channel channel, bool enable)
 {
 	mgr_fld_write(channel, DISPC_MGR_FLD_ENABLE, enable);