drm/msm/a6xx: Move CX GMU power counter enablement to hw_init

Since the introduction of A6xx support, we've been enabling the CX GMU
power counter 0 in a bit of a weird spot. Move it to hw_init so that
GMU wrapper GPUs can reuse the same code paths. As a bonus, this order
makes it easier to compare mainline and downstream register access traces.

Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/542765/


Signed-off-by: Rob Clark <robdclark@chromium.org>