tcp: remove dead code from tcp_sendmsg_locked()

TCP sendmsg() no longer puts payload in skb head, we can remove
dead code.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/tcp.c

@@ -1309,14 +1309,7 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
 		if (copy > msg_data_left(msg))
 			copy = msg_data_left(msg);
 
-		/* Where to copy to? */
-		if (skb_availroom(skb) > 0 && !zc) {
-			/* We have some space in skb head. Superb! */
-			copy = min_t(int, copy, skb_availroom(skb));
-			err = skb_add_data_nocache(sk, skb, &msg->msg_iter, copy);
-			if (err)
-				goto do_fault;
-		} else if (!zc) {
+		if (!zc) {
 			bool merge = true;
 			int i = skb_shinfo(skb)->nr_frags;
 			struct page_frag *pfrag = sk_page_frag(sk);
@@ -1416,7 +1409,6 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
 
 do_error:
 	skb = tcp_write_queue_tail(sk);
-do_fault:
 	tcp_remove_empty_skb(sk, skb);
 
 	if (copied + copied_syn)