Remove open flow controller connections on shutdown

Change-Id: I27895ea26a68dcfe395821f0492a292288ceb34b

@@ -174,6 +174,7 @@ public class OpenFlowControllerImpl implements OpenFlowController {
 
     @Deactivate
     public void deactivate() {
+        preDeactivate();
         cfgService.unregisterProperties(getClass(), false);
         connectedSwitches.clear();
         activeMasterSwitches.clear();