CHI.py was not working with Garnet as ruby_system.network.buffer_size only exists in SimpleNetwork. Change-Id: I00e952f8881d385e3591c149e08c9c7a53fda2cd Signed-off-by: Tiago Mück <tiago.muck@arm.com> Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/63811 Maintainer: Jason Lowe-Power <power.jg@gmail.com> Reviewed-by: Jason Lowe-Power <power.jg@gmail.com> Tested-by: kokoro <noreply+kokoro@google.com>