xfrm: Mark flowi arg to ->get_tos() 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 7a8e2c7..f8ccb97 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -1256,7 +1256,7 @@
  * still valid.
  */
 
-static inline int xfrm_get_tos(struct flowi *fl, int family)
+static inline int xfrm_get_tos(const struct flowi *fl, int family)
 {
 	struct xfrm_policy_afinfo *afinfo = xfrm_policy_get_afinfo(family);
 	int tos;