MastershipManager: lower log level

Change-Id: Iad51d87740ca08d3286be9bbb02b408cf8c4e97d
diff --git a/core/net/src/main/java/org/onlab/onos/cluster/impl/MastershipManager.java b/core/net/src/main/java/org/onlab/onos/cluster/impl/MastershipManager.java
index 0989867..dbb3ae4 100644
--- a/core/net/src/main/java/org/onlab/onos/cluster/impl/MastershipManager.java
+++ b/core/net/src/main/java/org/onlab/onos/cluster/impl/MastershipManager.java
@@ -269,7 +269,7 @@
 
         @Override
         public void notify(MastershipEvent event) {
-            log.info("dispatching mastership event {}", event);
+            log.trace("dispatching mastership event {}", event);
             eventDispatcher.post(event);
         }