Add xxhash functions. This is a very fast hash function, running at RAM
speed limits.
This code was adapted from the linux kernel with minor modifications to
make it fit in coreboot.
BUG=b:193557430
TEST=compile
Signed-off-by: Fred Reitberger <reitbergerfred@gmail.com>
Change-Id: I8108af5ab14d8e6c6f5859bd36155c7d254e892c
Reviewed-on: https://review.coreboot.org/c/coreboot/+/67300
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Martin Roth <martin.roth@amd.corp-partner.google.com>
