dt-bindings: PCI: qcom: Document the IPQ9574 PCIe controller

dt-bindings: PCI: qcom: Document the IPQ9574 PCIe controller

Document the PCIe controller on IPQ9574 platform.

Link: https://lore.kernel.org/r/20240801054803.3015572-2-quic_srichara@quicinc.com
Signed-off-by: devi priya <quic_devipriy@quicinc.com>
Signed-off-by: Sricharan Ramabadhran <quic_srichara@quicinc.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>