TCP: Fix setting of snd_ssthresh in tcp_mtu_probe_success

This looks like a simple typo that has gone unnoticed for some time.  The
impact is relatively low but it's clearly wrong.
Signed-off-by: John Heffner <johnwheffner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/tcp_input.c

@@ -2874,7 +2874,7 @@ static void tcp_mtup_probe_success(struct sock *sk)
 		       icsk->icsk_mtup.probe_size;
 	tp->snd_cwnd_cnt = 0;
 	tp->snd_cwnd_stamp = tcp_time_stamp;
-	tp->rcv_ssthresh = tcp_current_ssthresh(sk);
+	tp->snd_ssthresh = tcp_current_ssthresh(sk);
 
 	icsk->icsk_mtup.search_low = icsk->icsk_mtup.probe_size;
 	icsk->icsk_mtup.probe_size = 0;