net: Make RFS socket operations not be inet specific.

Idea from Eric Dumazet.

As for placement inside of struct sock, I tried to choose a place
that otherwise has a 32-bit hole on 64-bit systems.

Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 1e18f9c..fa3d287 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1217,7 +1217,7 @@
 	sk->sk_state = TCP_CLOSE;
 	inet->inet_daddr = 0;
 	inet->inet_dport = 0;
-	inet_rps_save_rxhash(sk, 0);
+	sock_rps_save_rxhash(sk, 0);
 	sk->sk_bound_dev_if = 0;
 	if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
 		inet_reset_saddr(sk);
@@ -1262,7 +1262,7 @@
 	int rc;
 
 	if (inet_sk(sk)->inet_daddr)
-		inet_rps_save_rxhash(sk, skb->rxhash);
+		sock_rps_save_rxhash(sk, skb->rxhash);
 
 	rc = sock_queue_rcv_skb(sk, skb);
 	if (rc < 0) {