drm/msm/a690: Fix reg values for a690

KGSL doesn't support a690 so all reg values were the same as
on a660. Now we know the values and they are different from the
windows driver.

This fixes hangs on D3D12 games and some CTS tests.

Signed-off-by: Danylo Piliaiev <dpiliaiev@igalia.com>
Signed-off-by: Rob Clark <robdclark@chromium.org>
Patchwork: https://patchwork.freedesktop.org/patch/568931/