[ONOS-6471] Port stats collector started two times, which is unnecessary

Change-Id: I08d56c70ba1629e2474883820fc4aa8af6b79c84
diff --git a/providers/openflow/device/src/main/java/org/onosproject/provider/of/device/impl/OpenFlowDeviceProvider.java b/providers/openflow/device/src/main/java/org/onosproject/provider/of/device/impl/OpenFlowDeviceProvider.java
index 2b003d1..53cf2e5 100644
--- a/providers/openflow/device/src/main/java/org/onosproject/provider/of/device/impl/OpenFlowDeviceProvider.java
+++ b/providers/openflow/device/src/main/java/org/onosproject/provider/of/device/impl/OpenFlowDeviceProvider.java
@@ -294,9 +294,6 @@
                 // disconnect to trigger switch-add later
                 sw.disconnectSwitch();
             }
-            PortStatsCollector psc = new PortStatsCollector(timer, sw, portStatsPollFrequency);
-            psc.start();
-            collectors.put(new Dpid(sw.getId()), psc);
         }
     }