asus-laptop: add wimax and wwan support

Asus UL30A has a 3G chip, but the radio is disabled by default.
The DSDT also reference a WIMAX device, which is not present on this model.

This patch adds two new files: wwan and wimax to control WWAN and
WIMAX devices. It does not use rfkill, because like WLED and BLED,
we don't know yet that the two ACPI functions will always control the
radio, they may control only the leds on some hardware.

We may add rfkill switchs later.

Signed-off-by: Corentin Chary <corentincj@iksaif.net>
Signed-off-by: Matthew Garrett <mjg@redhat.com>