arch-arm: Fix ArmISA namespace requirement for Arm KVM

This is needed after:

https://gem5-review.googlesource.com/c/public/gem5/+/34155

Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Change-Id: I614b908a48145d8c2f5e8b8177448e3269f8dac9
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/34418
Reviewed-by: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>
4 files changed