net: fix netconsole filtering

Adjustment of Michael Walle's fix patch

Commit 8a0eccb1 breaks netconsole. src_ip
must not be converted to host byte order, because nc_ip is already stored
in network byte order (see string_to_ip(), called by getenv_IPaddr()).

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>