drm/msm: Add speed-bin support to a618 gpu

Some GPUs support different max frequencies depending on the platform.
To identify the correct variant, we should check the gpu speedbin
fuse value. Add support for this speedbin detection to a6xx family
along with the required fuse details for a618 gpu.

Signed-off-by: Akhil P Oommen <akhilpo@codeaurora.org>
Reviewed-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>