dt-bindings: net: dsa: brcm,sf2: Drop unneeded "#address-cells/#size-cells"

There's no need for "#address-cells/#size-cells" in the brcm,sf2 node as
no immediate child nodes have an address. What was probably intended was
to put them in the 'ports' node, but that's not necessary as that is
covered by ethernet-switch.yaml via dsa.yaml.

Signed-off-by: Rob Herring <robh@kernel.org>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20230404204152.635400-1-robh@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>