sha/asm/keccak1600-mmx.pl: optimize for Atom and add comparison data.

Curiously enough out-of-order Silvermont benefited most from
optimization, 33%. [Originally mentioned "anomaly" turned to be
misreported frequency scaling problem. Correct results were
collected under older kernel.]

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
(Merged from https://github.com/openssl/openssl/pull/3739)