acer-wmi: add ACER_WMID_v2 interface flag to represent new notebooks

There have new acer notebooks' BIOS provide new WMID_GUID3 and
ACERWMID_EVENT_GUID methods.

Some of machines still keep the old WMID_GUID1 method but more and
more machines were already removed old wmi methods from DSDT.

So, this patch add a new ACER_WMID_v2 interface flag to represent
new acer notebooks, the following is definition:

 + ACER_WMID:
        It means this machine only provides WMID_GUID1/2 methods.

 + ACER_WMID_v2:
        It means this machine provide new WMID_GUID3 and WMID_EVENT_GUID
        methods.
        Some ACER_WMID_v2 machines also provide old WMID_GUID1/2 methods,
        but we still query/set communication device's state by new
        WMID_GUID3 method.

Tested on Acer Travelmate 8572
Tested on Acer Aspire 4739Z

Tested-by: AceLan Kao <acelan.kao@canonical.com>
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>
Cc: Thomas Renninger <trenn@suse.de>
Signed-off-by: Lee, Chun-Yi <jlee@suse.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>