dt-bindings: PCI: qcom: Document the SM8650 PCIe Controller

Document the PCIe Controller on the SM8650 platform by using the
SM8550 bindings as a fallback.

Link: https://lore.kernel.org/linux-pci/20231128-topic-sm8650-upstream-bindings-pcie-v2-1-b72e2d13bcf1@linaro.org
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>