Netboot full image loading AST2400

[Lei YU]

> It seems like there would an easy way to do this for development/bringup, asking instead of hacking on the code for a change.
>
> Im bringing up a system by loading an image via u-boot across the network into the upper section of ram, then booting from there. It relocates itself to the reset vector and generally works well.

You could refer to
https://lists.ozlabs.org/pipermail/openbmc/2017-December/010264.html
for TFTP kernel + NFS rootfs boot.