Based on a submission to the uboot-lantiq repo by Eddi De Pieri.
Major cleanup and addition of brnboot second stage u-boot was done by
me.
The second stage brnboot u-boot is untested, since the brnboot prompt
is secured by a still unknown password. But should work.
The former ram values are replaced with the ram values extracted from
the original brnboot. The old ones didn't worked with the ramboot
image.
Signed-off-by: Mathias Kresin <dev@kresin.me>