Merge branch '2022-12-05-add-IPv6-support'

Merge branch '2022-12-05-add-IPv6-support'

To quote the author:
This patch set adds basic IPv6 support to U-boot.
It is based on Chris's Packham patches
(https://lists.denx.de/pipermail/u-boot/2017-January/279366.html)
Chris's patches were taken as base. There were efforts to launch it on
HiFive SiFive Unmatched board but the board didn't work well. The code was
refactored, fixed some bugs as CRC for little-endian, some parts were implemented in
our own way, something was taken from Linux. Finally we did manual tests and the
board worked well.

Testing was done on HiFive SiFive Unmatched board (RISC-V)