Connections between cpu and gem5 lies in gic_hub now, but these are not related to gic. So I create a subsystem in fastmodel cluster named cpu_hub, and put those connections (a2t, t2g) there. Change-Id: I18d9f80ce6f7f7f4a8290d1db5e48962294f43e5 Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/61851 Maintainer: Jason Lowe-Power <power.jg@gmail.com> Tested-by: kokoro <noreply+kokoro@google.com> Reviewed-by: Yu-hsin Wang <yuhsingw@google.com> Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>