drm: msm: a6xx: fix gpu failure after system resume

On targets where GMU is available, GMU takes over the ownership of GX GDSC
during its initialization. So, move the refcount-get on GX PD before we
initialize the GMU. This ensures that nobody can collapse the GX GDSC
once GMU owns the GX GDSC. This patch fixes some GMU OOB errors seen
during GPU wake up during a system resume.

Reported-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Akhil P Oommen <akhilpo@codeaurora.org>
Tested-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>