OMAPDSS: check the return value of dss_mgr_enable()

Now that dss_mgr_enable returns an error value, check it in all the
places dss_mgr_enable is used, and bail out properly.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
diff --git a/drivers/video/omap2/dss/sdi.c b/drivers/video/omap2/dss/sdi.c
index 02da8be..8266ca0 100644
--- a/drivers/video/omap2/dss/sdi.c
+++ b/drivers/video/omap2/dss/sdi.c
@@ -123,10 +123,14 @@
 		goto err_sdi_enable;
 	mdelay(2);
 
-	dss_mgr_enable(dssdev->manager);
+	r = dss_mgr_enable(dssdev->manager);
+	if (r)
+		goto err_mgr_enable;
 
 	return 0;
 
+err_mgr_enable:
+	dss_sdi_disable();
 err_sdi_enable:
 err_set_dispc_clock_div:
 err_set_dss_clock_div: