net: Make flowi ports AF dependent.

Create two sets of port member accessors, one set prefixed by fl4_*
and the other prefixed by fl6_*

This will let us to create AF optimal flow instances.

It will work because every context in which we access the ports,
we have to be fully aware of which AF the flowi is anyways.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index e10f62e..116e4a8 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -778,7 +778,7 @@
 	if (!skb)
 		goto out;
 
-	err = udp_send_skb(skb, fl->fl4_dst, fl->fl_ip_dport);
+	err = udp_send_skb(skb, fl->fl4_dst, fl->fl4_dport);
 
 out:
 	up->len = 0;
@@ -917,8 +917,8 @@
 			.flowi_proto = sk->sk_protocol,
 			.flowi_flags = (inet_sk_flowi_flags(sk) |
 				     FLOWI_FLAG_CAN_SLEEP),
-			.fl_ip_sport = inet->inet_sport,
-			.fl_ip_dport = dport,
+			.fl4_sport = inet->inet_sport,
+			.fl4_dport = dport,
 		};
 		struct net *net = sock_net(sk);
 
@@ -973,9 +973,9 @@
 	 *	Now cork the socket to pend data.
 	 */
 	inet->cork.fl.fl4_dst = daddr;
-	inet->cork.fl.fl_ip_dport = dport;
+	inet->cork.fl.fl4_dport = dport;
 	inet->cork.fl.fl4_src = saddr;
-	inet->cork.fl.fl_ip_sport = inet->inet_sport;
+	inet->cork.fl.fl4_sport = inet->inet_sport;
 	up->pending = AF_INET;
 
 do_append_data: