dt-bindings: display/msm/gmu: Add Adreno 7[34]0 GMU

dt-bindings: display/msm/gmu: Add Adreno 7[34]0 GMU

The GMU on the A7xx series is pretty much the same as on the A6xx parts.
It's now "smarter", needs a bit less register writes and controls more
things (like inter-frame power collapse) mostly internally (instead of
us having to write to G[PM]U_[CG]X registers from APPS)

The only difference worth mentioning is the now-required DEMET clock,
which is strictly required for things like asserting reset lines, not
turning it on results in GMU not being fully functional (all OOB requests
would fail and HFI would hang after the first submitted OOB).

Describe the A730 and A740 GMU.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8550-QRD
Tested-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org> # sm8450
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/559278/
Signed-off-by: Rob Clark <robdclark@chromium.org>