drivers: net: fsl-mc: Include MAC addr fixup to DPL

Previous to MC v10.x, port mac address was specified via DPL. Since
newer MC versions are compatible with old style DPLs, make the u-boot
env mac addresses visible there. This applies only to DPLs that have
an older version.

DPLs use 32 bit values for specifying MAC addresses. U-boot
environment variables take precedence over the MAC addresses already
visible in the DPL/DPC.

Signed-off-by: Bogdan Purcareata <bogdan.purcareata@nxp.com>
Signed-off-by: Heinz Wrobel <heinz.wrobel@nxp.com>
Reviewed-by: York Sun <york.sun@nxp.com>