CFT: PMU-based speed changes

[Justin Hibbits]

After over a year of off-and-on work, lots of frustration, and help from
quite a few people, I present to you all for testing, PMU speed changes.
 You can find it in the projects/pmac_pmu branch, which is branched from
-CURRENT back in December/January.  Anybody with a Titanium Powerbook, and
some of the early Aluminum books, should now be able to run their machines
at full speed using powerd, or sysctl dev.cpu.0.freq.  I tested this on my
1GHz TiBook (last generation TiBook), using md5 on a core dump, and saw a
nice performance boost.

That branch also has PMU-based sleep code in place, but it does not work
(don't try to set sysctl dev.pmu.0.sleep, your machine will go catatonic).
 I haven't decided yet if I will commit what I have minus the sleep, or
wait until sleep is done.

As always, any comments and suggestions are welcome.

- Justin