drm/msm/a6xx: Fix up QMP handling

drm/msm/a6xx: Fix up QMP handling

The commit referenced in the Fixes tag had a couple problems (as
pointed out by Dan):

- qmp_put was never called, resulting in refcnt leaks
- failling to acquire the QMP mailbox on A7xx would not undo the probe
  function properly
- the qmp_put call present in the code was unreachable

Fix all of these issues.

Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Fixes: 88a0997f2f94 ("drm/msm/a6xx: Send ACD state to QMP at GMU resume")
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/562761/
Signed-off-by: Rob Clark <robdclark@chromium.org>