each FlowEntry instance should not have logger instance

Change-Id: Idd47696efa5df7015cb1e5f3d362577194351f0f

@@ -8,7 +8,7 @@ import org.slf4j.Logger;
 
 public class DefaultFlowEntry extends DefaultFlowRule implements FlowEntry {
 
-    private final Logger log = getLogger(getClass());
+    private static final Logger log = getLogger(DefaultFlowEntry.class);
 
     private long life;
     private long packets;

@@ -11,7 +11,7 @@ import org.slf4j.Logger;
 
 public class DefaultFlowRule implements FlowRule {
 
-    private final Logger log = getLogger(getClass());
+    private static final Logger log = getLogger(DefaultFlowRule.class);
 
     private final DeviceId deviceId;
     private final int priority;