[U-Boot] [PATCH v1 1/3] lib: Add xxhash support

[Marek Behun]

> Does xxhash.[ch] just come directly from Linux?  If so, we should
> convert them to SPDX tags _unless_ Linux has already decided not to as
> they in turn come directly from another project and the kernel folks
> don't want to mess with it at all.  Thanks!
> 

Hi Tom,
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/lib/xxhash.c?h=v5.1-rc7&id=5d2405227a9eaea48e8cc95756a06d407b11f141
this is the only commit in the kernel touching the xxhash sources. The
author only says this:

> I extracted it out from zstd since it is useful on its own. I copied
> the code from the upstream XXHash source repository and translated it
> into kernel style.

I think we can add SPDX tags to both xxhash and zstd sources. Do you
agree? Shall I post v2?

Marek