xfrm: Mark flowi arg to xfrm_type->reject() const.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index fa0b7f3..ccd47cf 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -1907,7 +1907,7 @@
 EXPORT_SYMBOL(xfrm_lookup);
 
 static inline int
-xfrm_secpath_reject(int idx, struct sk_buff *skb, struct flowi *fl)
+xfrm_secpath_reject(int idx, struct sk_buff *skb, const struct flowi *fl)
 {
 	struct xfrm_state *x;