Change "type" constant name

Change-Id: Ia8a070d5d1937b68c0e77be3741c5d8f47748e4c
diff --git a/src/main/java/net/onrc/onos/core/topology/DeviceImpl.java b/src/main/java/net/onrc/onos/core/topology/DeviceImpl.java
index f331b49..3c46656 100644
--- a/src/main/java/net/onrc/onos/core/topology/DeviceImpl.java
+++ b/src/main/java/net/onrc/onos/core/topology/DeviceImpl.java
@@ -133,6 +133,6 @@
     @Override
     public String getType() {
         // FIXME assuming device is always in packet layer for now.
-        return TopologyElement.TYPE_PACKET;
+        return TopologyElement.TYPE_PACKET_LAYER;
     }
 }