hwmon: Add Asus ATK0110 support

Asus boards have an ACPI interface for interacting with the hwmon (fan,
temperatures, voltages) subsystem; this driver exposes the relevant
information via the standard sysfs interface.

There are two different ACPI interfaces:
- an old one (based on RVLT/RFAN/RTMP)
- a new one (GGRP/GITM)
Both may be present but there a few cases (my board, sigh) where the
new interface is just an empty stub; the driver defaults to the old one
when both are present.
The old interface has received a considerable testing, but I'm still
awaiting confirmation from my tester that the new one is working as
expected (hence the debug code is still enabled).

Currently all the attributes are read-only, though a (partial) control
should be possible with a bit more work.

Signed-off-by: Luca Tettamanti <kronos.it@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>