[U-Boot] ls1021atwr: Convert to use driver model TSEC driver

[Bin Meng]

Hi York,

There was a patch [1] previously done by me to convert to use driver
model TSEC driver on LS1021ATWR. It was never accepted given at that
time the PCI driver for LS1021A has not been converted to use driver
model yet, and DM PCI is unfortunately bundled to DM ETH.

Now that we have converted to use DM PCI, would it possible for NXP
guys to pick up this work and do the DM ETH conversion for LS1021ATWR?
Thanks!

[1] http://patchwork.ozlabs.org/patch/566347/

Regards,
Bin