Intel turbo mode support

[Florian Unglaub]

Warren Block <wblock at wonkity.com> writes:
> Works here on an i5, amd64:
>
> dev.cpu.0.freq_levels: 5801/300000 5800/300000
>
> I found this by accident, noticing only that a buildworld suddenly was a
> lot faster when powerd was running.
>
> powerd_enable="YES"
> powerd_flags="-a hadp -n hadp"
> performance_cpu_freq="HIGH"

I tried it with your powerd flags and the performance_cpu_freq setting
on HIGH, but still the maximum freq_levels entry is 2800.

Florian