dt-bindings: qcom,pdc: document QCS615 Power Domain Controller

Add a compatible for the Power Domain Controller on QCS615 platform.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Lijuan Gao <quic_lijuang@quicinc.com>
Link: https://lore.kernel.org/r/20241104-add_initial_support_for_qcs615-v5-2-9dde8d7b80b0@quicinc.com


Signed-off-by: Rob Herring (Arm) <robh@kernel.org>