Fix NPE when ControlPlaneConnectPoint config is added after interface config

Change-Id: I31ee1d2e646d4b4c88ac5bb3b661228c893292b9

@@ -597,9 +597,12 @@ public class ControlPlaneRedirectManager {
     }
 
     private class InternalInterfaceListener implements InterfaceListener {
-
         @Override
         public void event(InterfaceEvent event) {
+            if (controlPlaneConnectPoint == null) {
+                log.info("Control plane connect point is not configured. Abort InterfaceEvent.");
+                return;
+            }
             Interface intf = event.subject();
             Interface prevIntf = event.prevSubject();
             switch (event.type()) {