[gpm] asus_laptop Light sensor

[Алексаненков Артём <alexanenkovad gmail com>]

When built-in light sensor disabled 

echo 0 > /sys/devices/platform/asus-laptop/ls_switch

I can adjust brightness with acpi_fakekey $KEY_BRIGHTNESSUP and
$KEY_BRIGHTNESSDOWN

When it's enabled ambient sensor work, but I can control it only by
setting ls_level directly in

/sys/devices/platform/asus-laptop/ls_level

Is it possible to make it work the same way using acpi_fakekey?