dt-bindings: net: ethernet-switch: Add missing 'ethernet-ports' level

dt-bindings: net: ethernet-switch: Add missing 'ethernet-ports' level

The '$defs/ethernet-ports' schema is referenced by schemas defining a
child node 'ethernet-ports', but this schema misses the
'ethernet-ports' node. It would work if referring schemas made a
reference like this:

properties:
  ethernet-ports:
    $ref: ethernet-switch.yaml#/$defs/ethernet-ports

However, that would be different from how dsa.yaml works. For
consistency, align the schema definition with dsa.yaml and add the
missing level.

Signed-off-by: Rob Herring <robh@kernel.org>
Acked-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20231016-dt-net-cleanups-v1-4-a525a090b444@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>