acer-wmi: schedule threeg and interface sysfs for feature removal

we can now autodetect internal 3G device and already have the threeg
rfkill device. So, we plan to remove threeg sysfs support for it's no
longer necessary.

We also plan to remove interface sysfs file that exposed which ACPI-WMI
interface that was used by acer-wmi driver. It will replaced by information
log when acer-wmi initial.

We keep it around for userspace compatibility reasons, schedule removal
in 2012.

Cc: Carlos Corbacho <carlos@strangeworlds.co.uk>
Cc: Matthew Garrett <mjg@redhat.com>
Cc: Dmitry Torokhov <dtor@mail.ru>
Cc: Corentin Chary <corentincj@iksaif.net>
Acked-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Lee, Chun-Yi <jlee@novell.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>