[IPSEC] xfrm: Use IPPROTO_MAX instead of 256

The size of the type_map array (256) comes from the number of IP protocols,
i.e., IPPROTO_MAX.  This patch is based on a suggestion from Ingo Oeser.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/xfrm.h

@@ -207,7 +207,7 @@ struct xfrm_type;
 struct xfrm_dst;
 struct xfrm_policy_afinfo {
 	unsigned short		family;
-	struct xfrm_type	*type_map[256];
+	struct xfrm_type	*type_map[IPPROTO_MAX];
 	struct xfrm_mode	*mode_map[XFRM_MODE_MAX];
 	struct dst_ops		*dst_ops;
 	void			(*garbage_collect)(void);