dt-bindings: PCI: rcar-pci-host: Add missing IOMMU properties

make dtbs_check:

    arch/arm64/boot/dts/renesas/r8a77951-salvator-xs.dtb: pcie@fe000000: Unevaluated properties are not allowed ('iommu-map', 'iommu-map-mask' were unexpected)
	    from schema $id: http://devicetree.org/schemas/pci/rcar-pci-host.yaml#

Fix this by adding the missing IOMMU-related properties.

[kwilczynski: added missing Fixes: tag]
Fixes: 0d69ce3c ("dt-bindings: PCI: rcar-pci-host: Convert bindings to json-schema")
Link: https://lore.kernel.org/linux-pci/babc878a93cb6461a5d39331f8ecfa654dfda921.1706802597.git.geert+renesas@glider.be


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Acked-by: Conor Dooley <conor.dooley@microchip.com>