dt-bindings: net: fec: add iommus property

iMX8QM have iommu. Add proerty 'iommus'.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240201-8qm_smmu-v2-2-3d12a80201a3@nxp.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>