dt-bindings: net: dsa: b53: add BCM53134 support

BCM53134 are B53 switches connected by MDIO.
Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/dsa/brcm,b53.yaml

@@ -19,6 +19,7 @@ properties:
       - const: brcm,bcm53115
       - const: brcm,bcm53125
       - const: brcm,bcm53128
+      - const: brcm,bcm53134
       - const: brcm,bcm5365
       - const: brcm,bcm5395
       - const: brcm,bcm5389