dt-bindings: interrupt-controller: qcom,pdc: document qcom,sm4450-pdc

Add SM4450 PDC, which will used in SM4450 DTS.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Tengfei Fan <quic_tengfan@quicinc.com>
Link: https://lore.kernel.org/r/20230922081026.2799-2-quic_tengfan@quicinc.com


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