dt-bindings: clock: qcom,gcc-sdm845: add parent power domain

Allow Qualcomm GCC to register its parent power domain (e.g. RPMHPD) to
properly pass performance state from children.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220513061347.46480-2-krzysztof.kozlowski@linaro.org