[CPUFREQ] Longhaul - Redo Longhaul ver. 2

Start using v2 version of Longhaul when available. It provides
voltage scaling and can use ACPI C3 state. That's curious. CPU
will not change frequency on ACPI C3 when v1 is in use, but it will
when v2 is used. Driver will return max frequency all the time if
this isn't true for all processors. There is strange thing with
mobile voltage. Looks like only Nehemiah (C3-M) supports it.
Earlier processors have different mobile VRM (in docs), but I can't
find any which is using it. Looks like all are using VRM 8.5. So
fail for non Nehemiah with mobile VRM.

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