[CPUFREQ] Longhaul - Add voltage scaling to driver

Rename option "dont_scale_voltage" to "scale_voltage" because
don't will be default.
Use "pos" for calculating voltage. In this way driver don't need
to know mV value or low level value. Simply min U is one pos and
max U is second pos. All pos between these two are used.
Assume that min U is for min f and max U for max f. For frequency
between min and max calculate pos based on difference between
current frequency and min f.
Values in mobile VRM table changed to values from
C3-M datasheet.

Signed-off-by: Rafa³ Bilski <rafalbilski@interia.pl>
Signed-off-by: Dave Jones <davej@redhat.com>