mem: Add Units to mem stats

Add units to mem stats except mem-ruby stats

Change-Id: Iab214b5d08eb1accc2b35af0c3aed7d30df5b5f3
Signed-off-by: Hoa Nguyen <hoanguyen@ucdavis.edu>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/39276
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>
20 files changed