net: tcp_input: Neaten DBGUNDO

Move the #ifdef into the static void function so that the use
of DBGUNDO is validated when FASTRETRANS_DEBUG <= 1.

Remove the now unnecessary #else and #define DBGUNDO.
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/tcp_input.c

@@ -2333,9 +2333,9 @@ static bool tcp_any_retrans_done(const struct sock *sk)
 	return false;
 }
 
-#if FASTRETRANS_DEBUG > 1
 static void DBGUNDO(struct sock *sk, const char *msg)
 {
+#if FASTRETRANS_DEBUG > 1
 	struct tcp_sock *tp = tcp_sk(sk);
 	struct inet_sock *inet = inet_sk(sk);
 
@@ -2357,10 +2357,8 @@ static void DBGUNDO(struct sock *sk, const char *msg)
 			 tp->packets_out);
 	}
 #endif
-}
-#else
-#define DBGUNDO(x...) do { } while (0)
 #endif
+}
 
 static void tcp_undo_cwnd_reduction(struct sock *sk, bool unmark_loss)
 {