dt-bindings: clock: qcom,rpmcc: convert to dtschema

Convert the Qualcomm RPM Clock Controller bindings to DT schema and
include it in parent's schema (SMD RPM).

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220401201035.189106-10-krzysztof.kozlowski@linaro.org