Devices without power management support

[Emmanuel Dreyfus <manu%netbsd.org@localhost>]

Hello

When a devices fails initialization, the xxx_attach() function may exit
early, before calling pmf_device_register().

The consequence is that any attempt to put the system to sleep fail with 
a "Devices without power management support: ..." message. 

Weird things happens, and I experienced situation where some devices
randomly or always fail initialization. This breaks sleeping mode.

I have patches to move the pmf_device_register() earlier in xxx_attach()
to workaround the problem in iwm(4) and ihidev(4) where I encounter the
problem, but perhaps the problem could be worked around globaly, by not
failing sleep mode if a driver did not call pmf_device_register()?

Of course the lack of a registered suspend handler may miss the expectation
of a system sleeping with reduced power, but on the other hand, being 
unable to sleep at all means even less power reduction.

-- 
Emmanuel Dreyfus
manu%netbsd.org@localhost