Enabling acpicpu(4) by default

[Jukka Ruohonen <jruohonen%iki.fi@localhost>]

Hello.

I would like to enable acpicpu(4) in the i386 and amd64 GENERIC kernels.
The following options(4) must be commented out for this:

        - INTEL_ONDEMAND_CLOCKMOD
        - ENHANCED_SPEEDSTEP
        - EST_FREQ_USERWRITE
        - POWERNOW_K7
        - POWERNOW_K8

As can be read from comments and CVS logs, the listed options are also
increasingly difficult to maintain. From a maintenance point of view, the
used linear interpolation was an improvement from the older table-based
approach, but there are cases where this overestimates the frequencies and
hence carries the risk of writing garbage values to the registers. Against
this, acpicpu(4) can be seen as going back to the roots; most of the existing
tables in "est.c" were actually collected from ACPI information.

Moreover, without acpicpu(4), NetBSD is not going to support such things as
C-states, AMD processors newer than K8, CPU thermal management, or TurboBoost.
No functionality will be lost, but the GENERIC kernels can not provide
out-of-the-box experience for both Pentium III and Core i7.

- Jukka.