dt-bindings: clock: Add Qcom SM6375 GPUCC

Add device tree bindings for graphics clock controller for Qualcomm
Technology Inc's SM6375 SoCs.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230208091340.124641-8-konrad.dybcio@linaro.org