dt-bindings: PCI: qcom,pcie-sc7280: Move SC7280 to dedicated schema

Move SC7280 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 exactly one MSI interrupt, instead of eight, because I
   could not find interrupt details for this model and current DTS uses
   one interrupt.

Link: https://lore.kernel.org/linux-pci/20240205-dt-bindings-pci-qcom-split-continued-v1-2-c333cab5eeea@linaro.org


Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Acked-by: Rob Herring <robh@kernel.org>