tcp: Split BUG_ON() in tcp_tso_should_defer() into two assertions

The two conditions triggering BUG_ON() are somewhat unrelated:
the tcp_skb_pcount() check is meant to catch TSO flaws, the
second one checks sanity of congestion window bookkeeping.

Split them into two separate BUG_ON() assertions on two lines,
so that we know which one actually triggers, when they do.
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/tcp_output.c

@@ -1944,7 +1944,8 @@ static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb,
 
 	in_flight = tcp_packets_in_flight(tp);
 
-	BUG_ON(tcp_skb_pcount(skb) <= 1 || (tp->snd_cwnd <= in_flight));
+	BUG_ON(tcp_skb_pcount(skb) <= 1);
+	BUG_ON(tp->snd_cwnd <= in_flight);
 
 	send_win = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq;