arch-riscv,misc: Add missing overrides for clang compilation

The Clang compiler returns "missing override" errors without these.

Change-Id: I62af6c338b000123c924f0b3205551579bd5aeb4
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/41913
Reviewed-by: Gabe Black <gabe.black@gmail.com>
Reviewed-by: Hoa Nguyen <hoanguyen@ucdavis.edu>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>
3 files changed