daemon: remove unnecesary restriction for listener fd

daemon: remove unnecesary restriction for listener fd

Since df076bdbcc ([PATCH] GIT: Listen on IPv6 as well, if available.,
2005-07-23), any file descriptor assigned to a listening socket was
validated to be within the range to be used in an FDSET later.

6573faff34 (NO_IPV6 support for git daemon, 2005-09-28), moves to
use poll() instead of select(), that doesn't have that restriction,
so remove the original check.

Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Acked-by: Phillip Wood <phillip.wood123@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>