dt-bindings: net: fec: Add imx8dxl description

The imx8dl FEC has the same programming model as the one on the imx8qxp.

Add the imx8dl compatible string.
Signed-off-by: Fabio Estevam <festevam@denx.de>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230926111017.320409-1-festevam@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/devicetree/bindings/net/fsl,fec.yaml

@@ -59,6 +59,7 @@ properties:
           - const: fsl,imx6sx-fec
       - items:
           - enum:
+              - fsl,imx8dxl-fec
               - fsl,imx8qxp-fec
           - const: fsl,imx8qm-fec
           - const: fsl,imx6sx-fec