drm/omap: use dispc_channel_connected in output drivers

Use 'out->dispc_channel_connected' to check if the device is connected
to an overlay manager or not, instead of using 'out->manager'.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

drivers/gpu/drm/omapdrm/dss/venc.c

@@ -515,7 +515,7 @@ static int venc_display_enable(struct omap_dss_device *dssdev)
 
 	mutex_lock(&venc.venc_lock);
 
-	if (out->manager == NULL) {
+	if (!out->dispc_channel_connected) {
 		DSSERR("Failed to enable display: no output/manager\n");
 		r = -ENODEV;
 		goto err0;