Schedule the link discovery task on startup.

src/main/java/net/floodlightcontroller/linkdiscovery/internal/LinkDiscoveryManager.java

@@ -309,9 +309,6 @@ IFloodlightModule, IInfoProvider, IHAListener {
 
         if (lldpClock == 0) {
             discoverOnAllPorts();
-            return;
-        } else {
-            discoverOnKnownLinkPorts();
         }
     }
 
@@ -1607,6 +1604,7 @@ IFloodlightModule, IInfoProvider, IHAListener {
             }}, "Topology Updates");
         updatesThread.start();
 
+        discoveryTask.reschedule(DISCOVERY_TASK_INTERVAL, TimeUnit.SECONDS);
         // Register for the OpenFlow messages we want to receive
         floodlightProvider.addOFMessageListener(OFType.PACKET_IN, this);
         floodlightProvider.addOFMessageListener(OFType.PORT_STATUS, this);