[XFRM]: Add XFRM_MODE_xxx for future use.

Transformation mode is used as either IPsec transport or tunnel.
It is required to add two more items, route optimization and inbound trigger
for Mobile IPv6.
Based on MIPL2 kernel patch.

This patch was also written by: Ville Nuorvala <vnuorval@tcs.hut.fi>

Signed-off-by: Masahide NAKAMURA <nakam@linux-ipv6.org>
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index 00bf86e..7627956 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -298,7 +298,7 @@
 
 	__u32			reqid;
 
-/* Mode: transport/tunnel */
+/* Mode: transport, tunnel etc. */
 	__u8			mode;
 
 /* Sharing mode: unique, this session only, this user only etc. */