acpitz: fan sensor

[Christoph Egger <Christoph_Egger%gmx.de@localhost>]

Hi!

Although ACPI Specification defines an ACPI device
for FANs, BIOS vendors and OEMs do their own thing.

By reading the ACPI dump I figured out that my
HP Pavillion dv9700 laptop features a fan sensor
in the ACPI Thermal Zone which is beyond of the ACPI
Spec.

This patch implements support for the fan sensor
including the limits:

http://www.netbsd.org/~cegger/driver_acpitz.diff


envstat shows
[acpitz0]
  Processor Thermal Zone:     56.000   95.000                       degC
                     fan:       2840                                 RPM

envstat -W shows
[acpitz0]
  Processor Thermal Zone:     55.000                                degC
                     fan:       2570     4500     2000               RPM

W/o my patch, envstat shows

[acpitz0]
     temperature:     55.000   95.000                       degC


Christoph