mem: missing override specifier

Change-Id: Ied4817bcda317826303a1bb688b41823b18b489b
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/18128
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
1 file changed