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: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
1 file changed