dt-bindings: PCI: qcom: Add SDX55 SoC

Add support for the PCIe controller on the Qcom SDX55 SoC to the binding.

Link: https://lore.kernel.org/r/20230308082424.140224-4-manivannan.sadhasivam@linaro.org


Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>