[XFRM]: Introduce a helper to compare id protocol.

Put the helper to header for future use.
Based on MIPL2 kernel patch.

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 7627956..5b364b0 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -9,6 +9,7 @@
 #include <linux/skbuff.h>
 #include <linux/socket.h>
 #include <linux/pfkeyv2.h>
+#include <linux/ipsec.h>
 #include <linux/in6.h>
 #include <linux/mutex.h>
 
@@ -835,6 +836,11 @@
 	return atomic_read(&x->tunnel_users);
 }
 
+static inline int xfrm_id_proto_match(u8 proto, u8 userproto)
+{
+	return (userproto == IPSEC_PROTO_ANY || proto == userproto);
+}
+
 /*
  * xfrm algorithm information
  */