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/include/net/route.h b/include/net/route.h
index 6361f93..47eb25a 100644
--- a/include/net/route.h
+++ b/include/net/route.h
@@ -201,18 +201,18 @@
 }
 
 extern int ip_route_input_common(struct sk_buff *skb, __be32 dst, __be32 src,
-				 u8 tos, struct net_device *devin, bool noref, bool nocache);
+				 u8 tos, struct net_device *devin, bool noref);
 
 static inline int ip_route_input(struct sk_buff *skb, __be32 dst, __be32 src,
 				 u8 tos, struct net_device *devin)
 {
-	return ip_route_input_common(skb, dst, src, tos, devin, false, false);
+	return ip_route_input_common(skb, dst, src, tos, devin, false);
 }
 
 static inline int ip_route_input_noref(struct sk_buff *skb, __be32 dst, __be32 src,
-				       u8 tos, struct net_device *devin, bool nocache)
+				       u8 tos, struct net_device *devin)
 {
-	return ip_route_input_common(skb, dst, src, tos, devin, true, nocache);
+	return ip_route_input_common(skb, dst, src, tos, devin, true);
 }
 
 extern void ipv4_update_pmtu(struct sk_buff *skb, struct net *net, u32 mtu,