dt-bindings: net: fsl,fec: Add i.MX8ULP FEC items

Add fsl,imx8ulp-fec for i.MX8ULP platform.
Signed-off-by: Wei Fang <wei.fang@nxp.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/all/20220726143853.23709-2-wei.fang@nxp.com/Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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

@@ -58,6 +58,11 @@ properties:
               - fsl,imx8qxp-fec
           - const: fsl,imx8qm-fec
           - const: fsl,imx6sx-fec
+      - items:
+          - enum:
+              - fsl,imx8ulp-fec
+          - const: fsl,imx6ul-fec
+          - const: fsl,imx6q-fec
 
   reg:
     maxItems: 1