dt-bindings: PCI: qcom: Document the X1E80100 PCIe Controller

Add dedicated schema for the PCIe controllers found on X1E80100.

Link: https://lore.kernel.org/linux-pci/20240301-x1e80100-pci-v4-1-7ab7e281d647@linaro.org


Signed-off-by: Abel Vesa <abel.vesa@linaro.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>