Power off for PCI devices

[Hasso Tepper]

http://leaf.dragonflybsd.org/~hasso/pci-detatch-powerdown.patch

With this tiny patch power is turned off for PCI devices during detach 
(ie. when you unload module). It makes is possible to preserve power in 
laptops (and make them cooler) with unloading network and/or sound device 
modules not in use and load them only if really needed.

However, I'm really not sure about all consequences this patch might 
cause, might knowledge about newbus and friends are still quite limited. 
Any objections to commit this?

Tested with em(4), ath(4) and snd_hda(4).


-- 
Hasso Tepper