Fixed hash method in CordVtnNode

- Hash method only uses hostname

Change-Id: Ibc8309374c8d22138349b651fcac4b6e2bf8b0e0

@@ -140,7 +140,7 @@ public final class CordVtnNode {
 
 
     @Override
     @Override
     public int hashCode() {
     public int hashCode() {
-        return Objects.hash(hostname, ovsdbIp, ovsdbPort);
+        return Objects.hash(hostname);
     }
     }
 
 
     @Override
     @Override