Due to a spin lock error affecting multicore timing cores, https://gem5.atlassian.net/browse/GEM5-1105, gem5 only supported single-core timing setups. As this has now been fixed, we support it. This patch expands the boot tests to include tests for multicore timing CPU systems. Change-Id: I89b7f1bed077373dae5e9b8eb6818129da915fee Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/55744 Reviewed-by: Austin Harris <mail@austin-harris.com> Reviewed-by: Jason Lowe-Power <power.jg@gmail.com> Maintainer: Jason Lowe-Power <power.jg@gmail.com> Maintainer: Bobby Bruce <bbruce@ucdavis.edu> Tested-by: kokoro <noreply+kokoro@google.com>