Update LearningSwitch.java

Working LearningSwitch.java

src/main/java/net/floodlightcontroller/learningswitch/LearningSwitch.java

@@ -53,6 +53,7 @@ import net.floodlightcontroller.debugcounter.IDebugCounterService;
 import net.floodlightcontroller.debugcounter.IDebugCounterService.MetaData;
 import net.floodlightcontroller.packet.Ethernet;
 import net.floodlightcontroller.restserver.IRestApiService;
+import net.floodlightcontroller.util.OFMessageUtils;
 
 import org.projectfloodlight.openflow.protocol.OFFlowMod;
 import org.projectfloodlight.openflow.protocol.OFFlowRemoved;