OMAPDSS: remove enum omap_dss_overlay_managers

We have two almost the same enums: omap_channel and
omap_dss_overlay_managers. omap_channel is used almost everywhere, and
omap_channel assigns explicit values to the enum values which are needed
for proper operation.

omap_dss_overlay_managers is only used in one place, so it's easy to
remove it, which is what this patch does.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
diff --git a/drivers/video/omap2/dss/overlay.c b/drivers/video/omap2/dss/overlay.c
index b0ba60f..c492bb0 100644
--- a/drivers/video/omap2/dss/overlay.c
+++ b/drivers/video/omap2/dss/overlay.c
@@ -530,10 +530,10 @@
 	struct omap_overlay_manager *lcd2_mgr = NULL;
 	struct omap_overlay_manager *mgr = NULL;
 
-	lcd_mgr = omap_dss_get_overlay_manager(OMAP_DSS_OVL_MGR_LCD);
-	tv_mgr = omap_dss_get_overlay_manager(OMAP_DSS_OVL_MGR_TV);
+	lcd_mgr = omap_dss_get_overlay_manager(OMAP_DSS_CHANNEL_LCD);
+	tv_mgr = omap_dss_get_overlay_manager(OMAP_DSS_CHANNEL_DIGIT);
 	if (dss_has_feature(FEAT_MGR_LCD2))
-		lcd2_mgr = omap_dss_get_overlay_manager(OMAP_DSS_OVL_MGR_LCD2);
+		lcd2_mgr = omap_dss_get_overlay_manager(OMAP_DSS_CHANNEL_LCD2);
 
 	if (dssdev->channel == OMAP_DSS_CHANNEL_LCD2) {
 		if (!lcd2_mgr->device || force) {