dt-bindings: net: ethernet-controller: document label property

"label" provides human readable name used on a box, board or schematic
to identify Ethernet port.
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220209082820.2210753-1-o.rempel@pengutronix.de

Documentation/devicetree/bindings/net/ethernet-controller.yaml

@@ -13,6 +13,10 @@ properties:
   $nodename:
     pattern: "^ethernet(@.*)?$"
 
+  label:
+    $ref: /schemas/types.yaml#/definitions/string
+    description: Human readable label on a port of a box.
+
   local-mac-address:
     description:
       Specifies the MAC address that was assigned to the network device.