drm/msm: crank down gpu when inactive

Shut down the clks when the gpu has nothing to do.  A short inactivity
timer is used to provide a low pass filter for power transitions.

Signed-off-by: Rob Clark <robdclark@gmail.com>

diff --cc drivers/gpu/drm/msm/adreno/a3xx_gpu.c
Simple merge

diff --cc drivers/gpu/drm/msm/msm_drv.c
Simple merge

diff --cc drivers/gpu/drm/msm/msm_gpu.c
Simple merge

diff --cc drivers/gpu/drm/msm/msm_gpu.h
Simple merge