mem-cache: Use SatCounter for prefetchers

Many prefetchers re-implement saturating counters with ints. Make
them use SatCounters instead.

Added missing operators and constructors to SatCounter for that to
be possible and their respective tests.

Change-Id: I36f10c89c27c9b3d1bf461e9ea546920f6ebb888
Signed-off-by: Daniel <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/17995
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Javier Bueno Hedo <javier.bueno@metempsy.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>

mem-cache: Added the Indirect Memory Prefetcher

Reference:
Xiangyao Yu, Christopher J. Hughes, Nadathur Satish, and Srinivas Devadas.
2015. IMP: indirect memory prefetcher. In Proceedings of the 48th
International Symposium on Microarchitecture (MICRO-48). ACM,
New York, NY, USA, 178-190. DOI: https://doi.org/10.1145/2830772.2830807

Change-Id: I52790f69c13ec55b8c1c8b9396ef9a1fb1be9797
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/16223
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>