stdlib: use atomic_noncaching when using AtomicSimpleCPU with Ruby

mem_mode is supposed to be atomic_noncaching when running
AtomicSimpleCPU with Ruby cache.

Change-Id: Icb419f9370038f5c1f80dd879b187338279a5b93
Signed-off-by: Hoa Nguyen <hoanguyen@ucdavis.edu>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/68877
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
2 files changed