This patch adds mcounteren, scounteren according to Risc-V Privileged Architectures V1.10. Change-Id: I6e138a50710bc0a1e9d9c38a11fc7fcc09ed500e Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/20128 Reviewed-by: Jason Lowe-Power <jason@lowepower.com> Reviewed-by: Alec Roelke <alec.roelke@gmail.com> Maintainer: Jason Lowe-Power <jason@lowepower.com> Maintainer: Alec Roelke <alec.roelke@gmail.com> Tested-by: kokoro <noreply+kokoro@google.com>