drm/msm: Enable expanded apriv support for a650

a650 supports expanded apriv support that allows us to map critical buffers
(ringbuffer and memstore) as as privileged to protect them from corruption.

Cc: stable@vger.kernel.org
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>