acer-wmi: allow 64-bits return buffer from WMI methods

Acer WMID_GUID1/2 method's return buffer was declared to 64-bits
on some Acer notebook, but WMI method only use 32-bits in return
buffer.
So, add this patch for allow 64-bits return buffer.

Reference: bko#34142
	https://bugzilla.kernel.org/show_bug.cgi?id=34142



Tested on Acer Travelmate 5735Z-452G32Mnss

Tested-by: Melchior FRANZ <melchior.franz@gmail.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@novell.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>