dt-bindings: PCI: renesas,pci-rcar-gen2: Add top-level constraints

dt-bindings: PCI: renesas,pci-rcar-gen2: Add top-level constraints

Properties with variable number of items per each device are expected to
have widest constraints in top-level "properties:" block and further
customized (narrowed) in "if:then:".

Add missing top-level constraints for clocks and clock-names.

Link: https://lore.kernel.org/linux-pci/20240818172843.121787-2-krzysztof.kozlowski@linaro.org
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>