[TCP]: Fix unlikely usage in tcp_transmit_skb()

The following unlikely should be replaced by likely because the
condition happens every time unless there is a hard error to transmit
a packet.

Signed-off-by: Hua Zhong <hzhong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index a28ae59..743016b 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -465,7 +465,7 @@
 	TCP_INC_STATS(TCP_MIB_OUTSEGS);
 
 	err = icsk->icsk_af_ops->queue_xmit(skb, 0);
-	if (unlikely(err <= 0))
+	if (likely(err <= 0))
 		return err;
 
 	tcp_enter_cwr(sk);