dt-bindings: arm: bcm: add bindings for ASUS RT-AC3100

Add ASUS RT-AC3100 under BCM47094 based boards.
Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230803071454.5902-1-arinc.unal@arinc9.comSigned-off-by: Florian Fainelli <florian.fainelli@broadcom.com>

Documentation/devicetree/bindings/arm/bcm/brcm,bcm4708.yaml

@@ -66,6 +66,7 @@ properties:
       - description: BCM47094 based boards
         items:
           - enum:
+              - asus,rt-ac3100
               - asus,rt-ac88u
               - dlink,dir-885l
               - dlink,dir-890l