cpu,mem: missing override specifier

Change-Id: I731d3ef021596450ac307461f215760a148bb28a
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/18348
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
Tested-by: kokoro <noreply+kokoro@google.com>
3 files changed