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>