dt-bindings: display/msm/gmu: account for different GMU variants

Make display/msm/gmu.yaml describe all existing GMU variants rather than
just the 630.2 (SDM845) version of it.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/492539/
Link: https://lore.kernel.org/r/20220706145222.1565238-4-dmitry.baryshkov@linaro.org


Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>