staging: lirc: remove checks for CONFIG_LIRC_SERIAL_NSLU2

When support for homebrew serial port receivers was added in v2.6.36 its
code contained checks for CONFIG_LIRC_SERIAL_NSLU2. The related Kconfig
symbol didn't exist then. It still doesn't exist now. Remove these checks.

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>