drm/msm: Fix the a650 hw_apriv check

Commit 604234f3 ("drm/msm: Enable expanded apriv support for a650")
was checking the result of adreno_is_a650() before the gpu revision
got probed in adreno_gpu_init() so it was always coming across as
false. Snoop into the revision ID ahead of time to correctly set the
hw_apriv flag so that it can be used by msm_gpu to properly setup
global buffers.

Fixes: 604234f3 ("drm/msm: Enable expanded apriv support for a650")
Reported-by: Jonathan Marek <jonathan@marek.ca>
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Tested-by: Jonathan Marek <jonathan@marek.ca>
Signed-off-by: Rob Clark <robdclark@chromium.org>