systemc: Add a missing override.

A recent change accidentally left off the override, upsetting gcc.

Change-Id: I78cf1969aa6ac462539a2793a8a91dea32002f3a
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/34756
Maintainer: Gabe Black <gabeblack@google.com>
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>
1 file changed