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/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 4d6717d..771f814 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1672,7 +1672,7 @@
 
 	skb->dev = NULL;
 
-	inet_rps_save_rxhash(sk, skb->rxhash);
+	sock_rps_save_rxhash(sk, skb->rxhash);
 
 	bh_lock_sock_nested(sk);
 	ret = 0;