mem-cache: Added the STeMS prefetcher

mem-cache: Added the STeMS prefetcher

Reference:
    Stephen Somogyi, Thomas F. Wenisch, Anastasia Ailamaki, and
    Babak Falsafi. 2009. Spatio-temporal memory streaming.
    In Proceedings of the 36th annual international symposium on
    Computer architecture (ISCA '09). ACM, New York, NY, USA, 69-80.

Change-Id: I58cea1a7faa9391f8aa4469eb4973feabd31097a
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/16423
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>