Also, add a comment mentioning _PSD - on some systems it's enough to
put one logical CPU into a particular P-state to make other CPUs in
the same domain to enter that P-state.
Also, call sched_unbind() after the loop - sched_bind() automatically
rebinds from previous CPU to a new one, and the new arrangement of code
is safer against early loop exit.
Plus one minor style nit.
MFC after: 10 days
shared and generalized between our current amd64, i386 and pc98.
This is just an initial step that should lead to a more complete effort.
For the moment, a very simple porting of cpufreq modules, BIOS calls and
the whole MD specific ISA bus part is added to the sub-tree but ideally
a lot of code might be added and more shared support should grow.
Sponsored by: Sandvine Incorporated
Reviewed by: emaste, kib, jhb, imp
Discussed on: arch
MFC: 3 weeks
