Fix: do not install default rules in gateway node

1. do not proceed without selectedGatewayNode having valid value

Change-Id: Ib092ab69360f7d985c5e52d9001a8e5f446cf6dc
diff --git a/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/OpenstackRoutingFloatingIpHandler.java b/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/OpenstackRoutingFloatingIpHandler.java
index 2b48baa..c122213 100644
--- a/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/OpenstackRoutingFloatingIpHandler.java
+++ b/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/OpenstackRoutingFloatingIpHandler.java
@@ -327,6 +327,7 @@
 
         if (selectedGatewayNode == null) {
             log.warn(ERR_FLOW + "no gateway node selected");
+            return;
         }
 
         switch (osNet.getNetworkType()) {
@@ -335,10 +336,6 @@
                     log.warn(ERR_FLOW + "no tunnel port");
                     return;
                 }
-                if (selectedGatewayNode == null) {
-                    log.warn(ERR_FLOW + "no gateway node");
-                    return;
-                }
                 sBuilder.matchTunnelId(Long.parseLong(osNet.getProviderSegID()));
                 tBuilder.extension(buildExtension(
                         deviceService,