dt-bindings: arm: ixp4xx: List actiontec devices

Add two IXP4xx device families from OpenWrts backlog:
Actiontec MI424WR revision A/C and revision D, both
of these are IXP4xx devices.

Revisions E and later use different chipsets.

Acked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/20250822-ixp4xx-mi424wr-dts-v2-2-cc804884474d@linaro.org

Documentation/devicetree/bindings/arm/intel-ixp4xx.yaml

@@ -16,6 +16,8 @@ properties:
     oneOf:
       - items:
           - enum:
+              - actiontec,mi424wr-ac
+              - actiontec,mi424wr-d
               - adieng,coyote
               - arcom,vulcan
               - dlink,dsm-g600-a