Remove unnecessary static from enum

Change-Id: Ie2f356c47d7d85100b789a15d913502868d95e8a
diff --git a/core/api/src/main/java/org/onosproject/net/PortNumber.java b/core/api/src/main/java/org/onosproject/net/PortNumber.java
index e1a1554..df45c54 100644
--- a/core/api/src/main/java/org/onosproject/net/PortNumber.java
+++ b/core/api/src/main/java/org/onosproject/net/PortNumber.java
@@ -52,7 +52,7 @@
     /**
      * Logical PortNumbers.
      */
-    public static enum Logical {
+    public enum Logical {
         IN_PORT(IN_PORT_NUMBER),
         TABLE(TABLE_NUMBER),
         NORMAL(NORMAL_NUMBER),