Remove open flow controller connections on shutdown

Change-Id: I27895ea26a68dcfe395821f0492a292288ceb34b
diff --git a/protocols/openflow/ctl/src/main/java/org/onosproject/openflow/controller/impl/OpenFlowControllerImpl.java b/protocols/openflow/ctl/src/main/java/org/onosproject/openflow/controller/impl/OpenFlowControllerImpl.java
index 84d2b9f..3062596 100644
--- a/protocols/openflow/ctl/src/main/java/org/onosproject/openflow/controller/impl/OpenFlowControllerImpl.java
+++ b/protocols/openflow/ctl/src/main/java/org/onosproject/openflow/controller/impl/OpenFlowControllerImpl.java
@@ -174,6 +174,7 @@
 
     @Deactivate
     public void deactivate() {
+        preDeactivate();
         cfgService.unregisterProperties(getClass(), false);
         connectedSwitches.clear();
         activeMasterSwitches.clear();