Revert "ipv4: tcp: dont cache unconfirmed intput dst"

This reverts commit c074da2810c118b3812f32d6754bd9ead2f169e7.

This change has several unwanted side effects:

1) Sockets will cache the DST_NOCACHE route in sk->sk_rx_dst and we'll
   thus never create a real cached route.

2) All TCP traffic will use DST_NOCACHE and never use the routing
   cache at all.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/xfrm4_input.c b/net/ipv4/xfrm4_input.c
index eee636b..06814b6 100644
--- a/net/ipv4/xfrm4_input.c
+++ b/net/ipv4/xfrm4_input.c
@@ -28,7 +28,7 @@
 		const struct iphdr *iph = ip_hdr(skb);
 
 		if (ip_route_input_noref(skb, iph->daddr, iph->saddr,
-					 iph->tos, skb->dev, false))
+					 iph->tos, skb->dev))
 			goto drop;
 	}
 	return dst_input(skb);