dt-bindings: display/msm/gmu: Add Adreno X185 GMU

Document Adreno X185 GMU in the dt-binding specification.

Signed-off-by: Akhil P Oommen <quic_akhilpo@quicinc.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Patchwork: https://patchwork.freedesktop.org/patch/601395/


Signed-off-by: Rob Clark <robdclark@chromium.org>