[TCP]: Add missing skb_header_release() call to tcp_fragment().

When we add any new packet to the TCP socket write queue,
we must call skb_header_release() on it in order for the
TSO sharing checks in the drivers to work.
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/tcp_output.c

@@ -655,6 +655,7 @@ static int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len)
 	}
 
 	/* Link BUFF into the send queue. */
+	skb_header_release(buff);
 	__skb_append(skb, buff);
 
 	return 0;