[XFRM]: Cleanup xfrm_msg_min and xfrm_dispatch

Converts xfrm_msg_min and xfrm_dispatch to use c99 designated
initializers to make greping a little bit easier. Also replaces
two hardcoded message type with meaningful names.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/xfrm.h b/include/linux/xfrm.h
index 4d19b9e..fd2ef74 100644
--- a/include/linux/xfrm.h
+++ b/include/linux/xfrm.h
@@ -144,6 +144,8 @@
 };
 #define XFRM_MSG_MAX (__XFRM_MSG_MAX - 1)
 
+#define XFRM_NR_MSGTYPES (XFRM_MSG_MAX + 1 - XFRM_MSG_BASE)
+
 struct xfrm_user_tmpl {
 	struct xfrm_id		id;
 	__u16			family;