xfrm: use secpath_exist where applicable

Will reduce noise when skb->sp is removed later in this series.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/net/xfrm.h

@@ -1185,7 +1185,7 @@ static inline int __xfrm_policy_check2(struct sock *sk, int dir,
 	if (sk && sk->sk_policy[XFRM_POLICY_IN])
 		return __xfrm_policy_check(sk, ndir, skb, family);
 
-	return	(!net->xfrm.policy_count[dir] && !skb->sp) ||
+	return	(!net->xfrm.policy_count[dir] && !secpath_exists(skb)) ||
 		(skb_dst(skb)->flags & DST_NOPOLICY) ||
 		__xfrm_policy_check(sk, ndir, skb, family);
 }

net/xfrm/xfrm_interface.c

@@ -251,7 +251,7 @@ static int xfrmi_rcv_cb(struct sk_buff *skb, int err)
 	struct xfrm_if *xi;
 	bool xnet;
 
-	if (err && !skb->sp)
+	if (err && !secpath_exists(skb))
 		return 0;
 
 	x = xfrm_input_state(skb);