net: fsl-mc: fixup DPC: add /board/ports node if missing

The DPC fixup for MAC address and enet_if is not made if
/board/ports node is missing in DPC file.
Add /board/ports or /ports nodes if them are missing.

Signed-off-by: Razvan Ionut Cirjan <razvanionut.cirjan@nxp.com>
Reviewed-by: Ioana Ciornei <Ioana.ciornei@nxp.com>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>