[ACPI] driverfs support for fans

[Dominik B. <de...@br...>]

Hi Paul, Hi Pat!

Attached is some preliminary driverfs support for acpi_fan.c. Both of you 
probably won't like some aspects of it:

x Parent of fan devices is device_sys of Pavel Machek's latest patchset (so 
you need that to get this patch compiled), when Pat's 
"register_sys_device"-patch is available using that should be straightforward 
(see #1 in "TBD").

x All fan devices are included in /devices/sys/, and so ACPI-2.0-specific 
fans for special parts of the systems appear there, too. I suggest that in 
future fans that are "below" any other device will simply have that device as 
parent, and fans that are "system-wide" will be devices of the system bus 
(see #2 in TBD).

Comments appreciated. 

Dominik