Add type code into LispType enum to prevent arbitrary place holder

With the existing implementation, if we want to specify type value
8 to ECM Lisp type, we need to generate several place holders
inside LispType enumerator, otherwise ECM will be assigned a
subsequent number which is 5.
With this commit, we can specify arbitrary number for each Lisp
enum type, therefore, no need to add redundant placeholder for
the purpose of incrementing enum value.

Change-Id: I82a82a3f5bc313dc1f79aaa66a77889408e8c891
diff --git a/protocols/lisp/msg/src/main/java/org/onosproject/lisp/msg/protocols/DefaultLispMapRegister.java b/protocols/lisp/msg/src/main/java/org/onosproject/lisp/msg/protocols/DefaultLispMapRegister.java
index 1d63782..7ccc7b6 100644
--- a/protocols/lisp/msg/src/main/java/org/onosproject/lisp/msg/protocols/DefaultLispMapRegister.java
+++ b/protocols/lisp/msg/src/main/java/org/onosproject/lisp/msg/protocols/DefaultLispMapRegister.java
@@ -296,7 +296,6 @@
      */
     public static class RegisterWriter implements LispMessageWriter<LispMapRegister> {
 
-        private static final int REGISTER_MSG_TYPE = 3;
         private static final int REGISTER_SHIFT_BIT = 4;
 
         private static final int PROXY_MAP_REPLY_SHIFT_BIT = 3;
@@ -310,7 +309,7 @@
         public void writeTo(ByteBuf byteBuf, LispMapRegister message) throws LispWriterException {
 
             // specify LISP message type
-            byte msgType = (byte) (REGISTER_MSG_TYPE << REGISTER_SHIFT_BIT);
+            byte msgType = (byte) (LispType.LISP_MAP_REGISTER.getTypeCode() << REGISTER_SHIFT_BIT);
 
             // proxy map reply flag
             byte proxyMapReply = DISABLE_BIT;