LBAAS config generation on controller

wrong reference is updated in LoadbalancerListenerSM.delete()
It should be loadbalancer_pool instead of loadbalancer_listener

Change-Id: I0c8e38a37c98bef449ba72485c613a0ec683957e
Partial-Bug: #1557222

src/config/svc-monitor/svc_monitor/config_db.py

@@ -87,7 +87,7 @@ def delete(cls, uuid):
             return
         obj = cls._dict[uuid]
         obj.update_single_ref('loadbalancer', {})
-        obj.update_single_ref('loadbalancer_listener', {})
+        obj.update_single_ref('loadbalancer_pool', {})
         del cls._dict[uuid]
     # end delete
 # end class LoadbalancerListenerSM