[IPSEC]: Fix bogus usage of u64 on input sequence number

Al Viro spotted a bogus use of u64 on the input sequence number which
is big-endian.  This patch fixes it by giving the input sequence number
its own member in the xfrm_skb_cb structure.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/ah6.c b/net/ipv6/ah6.c
index 379c8e0..2ff0c82 100644
--- a/net/ipv6/ah6.c
+++ b/net/ipv6/ah6.c
@@ -283,7 +283,7 @@
 
 	ah->reserved = 0;
 	ah->spi = x->id.spi;
-	ah->seq_no = htonl(XFRM_SKB_CB(skb)->seq);
+	ah->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output);
 
 	spin_lock_bh(&x->lock);
 	err = ah_mac_digest(ahp, skb, ah->auth_data);