base: Templatize SatCounter

base: Templatize SatCounter

Allow SatCounter to have larger unsigned types to accomodate
larger counters.

The template decision was taken because some predictors will
generate huge arrays of small counters, so smaller types will
lessen their overhead; however, isolated counters may require
any counter size.

Jira: https://gem5.atlassian.net/browse/GEM5-813

Change-Id: I5475a565ea7b97d1dfc176fa9d7cf827560fbe39
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/37135
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>