dtschema package with core schemas deprecated pci-bus.yaml schema in
favor of individual schemas per host, device and pci-pci.
Switch Mediatek MT7621 PCIe host bridge binding to this new schema.
This requires dtschema package newer than v2024.02 to work fully.
v2024.02 will partially work: with a warning.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>