From: Bruno Ducrot <ducrot@poupinou.org>

I think this patch is needed especially if the FSB is around 166MHz or
200MHz, or else I believe we get instabilities on some K7's motherboard
powernow capable (it's called Cool'n Quiet IIRC).
                                                                                         
                                                                                         
* Deduce fsb from cpu_khz and the max multiplier.  It will be given as kHz now,
  so that frequency associated to a multiplier will be computate more
  accurately.  Also, we need it for SGTC (see below).
* Fix how cpuid is computed in powernow_decode_bios().
* Be more restrictive for PST.  It may be possible (on desktop shipped with
  low power Athlon models) that FSB can be changed by dip switchs on
  motherboard for example.
* Fix computation for SGTC.  It use the bus timer (and then the bus
  frequency given by fsb).