KGSL: Add a simple GPU governor for Adreno xxx GPU series
KGSL: make simple govenor a selectable option, co-exist with ondemand

also removed some hardcoded values

Signed-off-by: Paul Reioux <reioux@gmail.com>
KGSL: Simple Governor: so I kinda butchered in a good way of course
the original code from faux, but the simplicity is still here. Added an history so that we can track the average do that the frequency scaling is much more proportional to the actual GPU load rather than having is ramp up every now and the due to spurious load spike. Also remove two useless ifs.
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
Enable the Simple GPU Governor by default