[CPUFREQ] Enhanced PowerSaver driver

This is driver for Enhanced Powersaver which is present in VIA C7
processors. Beta tested by Jorgen (jorgen (at) greven dot dk).
Thanks! Based on documentation provided by Dave Jones (Thanks!)
and C7 Eden datasheet available from www.via.com.tw. Looks like all
these C7 Eden CPU's don't have P-states in BIOS. I know that 2
p-states is low, but Jorgen finds it usefull anyway because board
is passive cooled.
There are 3 different types of C7 processors (called brands):
0. C7-M - these processors can set any maultiplier between min and
max, any voltage between min and max.
1. C7 - only min and max states are supported. Voltage is different
for min and max states.
2. Eden - only min and max states are supported. Looks like this
brand can only change multiplier. Voltage seems to be the same for
min and max frequency.

Signed-off-by: Rafal Bilski <rafalbilski@interia.pl>
Signed-off-by: Dave Jones <davej@redhat.com>