Move SM8450 PCIe devices from qcom,pcie.yaml binding to a dedicated file
to make reviewing easier.

This creates equivalent schema file, except:
 - Missing required compatible which is actually redundant.
 - Expecting eight MSI interrupts, instead of only one, which was
   incomplete hardware description.

Link: https://lore.kernel.org/linux-pci/20240126-dt-bindings-pci-qcom-split-v3-2-f23cda4d74c0@linaro.orgSigned-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>