Fixed to not to create gateway group if it is already exists

Also changed some names shorter.

Change-Id: Iaa8aa5ac378fc168e79c9e238090ca817af42261
diff --git a/apps/openstacknetworking/routing/src/main/java/org/onosproject/openstacknetworking/routing/OpenstackPnatHandler.java b/apps/openstacknetworking/routing/src/main/java/org/onosproject/openstacknetworking/routing/OpenstackPnatHandler.java
index 137c090..5af208d 100644
--- a/apps/openstacknetworking/routing/src/main/java/org/onosproject/openstacknetworking/routing/OpenstackPnatHandler.java
+++ b/apps/openstacknetworking/routing/src/main/java/org/onosproject/openstacknetworking/routing/OpenstackPnatHandler.java
@@ -147,11 +147,11 @@
 
         ScalableGatewayService gatewayService = getService(ScalableGatewayService.class);
         GatewayNode gatewayNode = gatewayService.getGatewayNode(deviceId);
-        if (gatewayNode.getGatewayExternalInterfaceName() == null) {
+        if (gatewayNode.getUplinkIntf() == null) {
             log.error(EXTERNAL_PORT_NULL, deviceId.toString());
             return;
         }
-        treatment.setOutput(gatewayService.getGatewayExternalPort(deviceId));
+        treatment.setOutput(gatewayService.getUplinkPort(deviceId));
 
         ethernet.resetChecksum();