eeepc-wmi: add rfkill support for wlan, bluetooth and 3g

wimax support is missing because I don't have any DSDT
with WMI and wimax support.

Most of the code comes from eeepc-laptop.

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