dt-bindings: clock: qcom: add bindings for dispcc on SM8450

Add device tree bindings for the display clock controller on Qualcomm
SM8450 platform.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20220908222850.3552050-2-dmitry.baryshkov@linaro.org