drm/msm/a6xx: Add A610 support

drm/msm/a6xx: Add A610 support

A610 is one of (if not the) lowest-tier SKUs in the A6XX family. It
features no GMU, as it's implemented solely on SoCs with SMD_RPM.
What's more interesting is that it does not feature a VDDGX line
either, being powered solely by VDDCX and has an unfortunate hardware
quirk that makes its reset line broken - after a couple of assert/
deassert cycles, it will hang for good and will not wake up again.

This GPU requires mesa changes for proper rendering, and lots of them
at that. The command streams are quite far away from any other A6XX
GPU and hence it needs special care. This patch was validated both
by running an (incomplete) downstream mesa with some hacks (frames
rendered correctly, though some instructions made the GPU hangcheck
which is expected - garbage in, garbage out) and by replaying RD
traces captured with the downstream KGSL driver - no crashes there,
ever.

Add support for this GPU on the kernel side, which comes down to
pretty simply adding A612 HWCG tables, altering a few values and
adding a special case for handling the reset line.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/542779/
Signed-off-by: Rob Clark <robdclark@chromium.org>