mem-ruby: Added upstream_nodes to AbstractController

Added support for an upstream_nodes NetAddr list in AbstractController,
which will be used in future CHI work.

JIRA: https://gem5.atlassian.net/browse/GEM5-1097

Change-Id: I30a6d621d7f201d89f0b13dab8ed4dd1f1f6caa3
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/57296
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
3 files changed