ipv4: fix ipsec forward performance regression

There is bug in commit 5e2b61f7(ipv4: Remove flowi from struct rtable).
It makes xfrm4_fill_dst() modify wrong data structure.
Signed-off-by: NZheng Yan <zheng.z.yan@intel.com>
Reported-by: NKim Phillips <kim.phillips@freescale.com>
Acked-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/xfrm4_policy.c

@@ -79,13 +79,13 @@ static int xfrm4_fill_dst(struct xfrm_dst *xdst, struct net_device *dev,
 	struct rtable *rt = (struct rtable *)xdst->route;
 	const struct flowi4 *fl4 = &fl->u.ip4;
 
-	rt->rt_key_dst = fl4->daddr;
-	rt->rt_key_src = fl4->saddr;
-	rt->rt_key_tos = fl4->flowi4_tos;
-	rt->rt_route_iif = fl4->flowi4_iif;
-	rt->rt_iif = fl4->flowi4_iif;
-	rt->rt_oif = fl4->flowi4_oif;
-	rt->rt_mark = fl4->flowi4_mark;
+	xdst->u.rt.rt_key_dst = fl4->daddr;
+	xdst->u.rt.rt_key_src = fl4->saddr;
+	xdst->u.rt.rt_key_tos = fl4->flowi4_tos;
+	xdst->u.rt.rt_route_iif = fl4->flowi4_iif;
+	xdst->u.rt.rt_iif = fl4->flowi4_iif;
+	xdst->u.rt.rt_oif = fl4->flowi4_oif;
+	xdst->u.rt.rt_mark = fl4->flowi4_mark;
 
 	xdst->u.dst.dev = dev;
 	dev_hold(dev);