[CPUFREQ] Longhaul - Embedded "conservative"

Longhaul with voltage scaling enabled works great on Ezra
CPU (Longhaul ver. 2). As long as "conservative" governor is
used. Both "ondemand" and "userspace" can change voltage
from min to max at once. Motherboard unfortunatly turns off
when vid difference is big. Longhaul was printing warning
message, but it is not enough. Now driver will have
"conservative" governor built in and will split bigger
changes to smaller ones.

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