staging: media/lirc: switch to use gpiolib

The lirc serial module has special hooks to work with NSLU2,
switch these over to use gpiolib, as that is available on the
ixp4 platform.

Not even compile tested as there is no way to select this
driver from menuconfig on the ixp4 platform.

Cc: Imre Kaloz <kaloz@openwrt.org>
Cc: Alexandre Courbot <acourbot@nvidia.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Krzysztof Halasa <khc@pm.waw.pl>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>