Add an option to add a PMU to the CPUs in `starter_fs.py` and `baremetal.py`. By default PMUs will not be added. Also adds an `--arm-ppi-number` option. Each PMU will be connected to its core using the specified PPI. Change-Id: I9cfb5781f211338919550f2320a7133d88801f6a Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/69957 Tested-by: kokoro <noreply+kokoro@google.com> Reviewed-by: Jason Lowe-Power <power.jg@gmail.com> Maintainer: Bobby Bruce <bbruce@ucdavis.edu>