eeepc-laptop: sync eeepc-laptop with asus_acpi

In the default Eee PC distribution, there is a modified
asus_acpi driver. eeepc-laptop is a cleaned version of this
driver. Sync ASL enum and getter/setters with asus_acpi.

Signed-off-by: Corentin Chary <corentincj@iksaif.net>
Signed-off-by: Len Brown <len.brown@intel.com>