Changed LLDP's in topodiscovery to real src mac

Was sending all zeros for the LLDP's source mac
address.  Changed to use the sending interface's
MAC as advertised from OFPhysicalPort

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

@@ -298,7 +298,7 @@ public class LinkDiscoveryManager
         }
 
         Ethernet ethernet = new Ethernet()
-            .setSourceMACAddress(new byte[6])
+            .setSourceMACAddress(port.getHardwareAddress())
             .setDestinationMACAddress(dstMacAddress)
             .setEtherType(Ethernet.TYPE_LLDP);
         // using "nearest customer bridge" MAC address for broadest possible propagation