use termService field

Change-Id: I56998905db4f0403e8c244937a788555dea37823
diff --git a/core/net/src/main/java/org/onlab/onos/net/device/impl/DeviceManager.java b/core/net/src/main/java/org/onlab/onos/net/device/impl/DeviceManager.java
index af59abd..dfff752 100644
--- a/core/net/src/main/java/org/onlab/onos/net/device/impl/DeviceManager.java
+++ b/core/net/src/main/java/org/onlab/onos/net/device/impl/DeviceManager.java
@@ -254,8 +254,7 @@
 //                }
                 return;
             }
-            MastershipTerm term = mastershipService.requestTermService()
-                    .getMastershipTerm(deviceId);
+            MastershipTerm term = termService.getMastershipTerm(deviceId);
 
             final NodeId myNodeId = clusterService.getLocalNode().id();
             if (!myNodeId.equals(term.master())) {