Fix a bug in the Link Discovery module when a switch is disconnected.

Apparently, if the switch is disconnected from the controller and
then reconnected, the discovered link state in the LinkDiscoveryManager
is not cleaned-up properly.
As a result, the links are not published when the switch reconnects.

Depends on timing, the links might actually be removed from the
Topology Manager, but won't be added back.

Change-Id: I2c1e1da9190047a93bd917c79bac9babeeb4ef6f
diff --git a/src/main/java/net/onrc/onos/core/linkdiscovery/LinkDiscoveryManager.java b/src/main/java/net/onrc/onos/core/linkdiscovery/LinkDiscoveryManager.java
index 8ffe4ee..42c2942 100644
--- a/src/main/java/net/onrc/onos/core/linkdiscovery/LinkDiscoveryManager.java
+++ b/src/main/java/net/onrc/onos/core/linkdiscovery/LinkDiscoveryManager.java
@@ -798,13 +798,7 @@
      */
     @Override
     public void switchDisconnected(long swId) {
-        IOFSwitch sw = floodlightProvider.getSwitch(swId);
-        if (sw == null) {
-            log.warn("Removed switch not available {} ", swId);
-            return;
-        }
-        // Update event history
-
+        // Cleanup link state
         List<Link> eraseList = new ArrayList<Link>();
         lock.writeLock().lock();
         try {