dt-bindings: net: renesas,ether: Add iommus property

make dtbs_check:

    arch/arm64/boot/dts/renesas/r8a77980-condor.dtb: ethernet@e7400000: 'iommus' does not match any of the regexes: '@[0-9a-f]$', 'pinctrl-[0-9]+'
	    from schema $id: http://devicetree.org/schemas/net/renesas,ether.yaml#

Ethernet Controllers on R-Car Gen2/Gen3 SoCs can make use of the IOMMU,
so add the missing iommus property.

Signed-off-by: Geert Uytterhoeven <[email protected]>
Reviewed-by: Niklas Söderlund <[email protected]>
Reviewed-by: Sergei Shtylyov <[email protected]>
Acked-by: Rob Herring (Arm) <[email protected]>
Link: https://patch.msgid.link/2ca890323477a21c22e13f6a1328288f4ee816f9.1729868894.git.geert+renesas@glider.be
Signed-off-by: Jakub Kicinski <[email protected]>

Author: geertu

Documentation/devicetree/bindings/net/renesas,ether.yaml

@@ -59,6 +59,9 @@ properties:
   clocks:
     maxItems: 1
 
+  iommus:
+    maxItems: 1
+
   power-domains:
     maxItems: 1