mali: improve usage of qos requirements in mali driver
mali: report correct mali voltage based on current OPP
mali: improve mali boost logic, give more meaningful variable names

boost switching logic:
- boost_working means that freq is already set to high value
- boost_scheduled means that job is scheduled to turn boost either on or off
- boost_required is a flag for scheduled job telling it what to do with boost

if we are in APE_50_OPP, skip boost and use default APE 50/100 logic
if we are in APE_100_OPP and util>boost_up_thresh, shedule boost if
its not on or - if its on and scheduled to be turned off -  cancel that schedule
if boost is scheduled and not yet working and util < util_high_to_low, then cancel scheduled boost
if boost is on and util < boost_down_thresh, schedule boost to be turned off
mali: remove mali_boost qos requirements

with now corrected mali_boost logic there is no
threat of going into ape_50_opp (and this low voltage)
with boosted clock
mali: allow changing APE_50_OPP voltage
Merge pull request #22 from mkaluza/mali

mali_boost improvements

Thanks @mkaluza