configs: Update Arm starter_se.py for new CpuCluster abstraction

Changeset [1] introduced a new CpuCluster abstraction. This requires
some changes to the Arm `starter_se.py` and `devices.py`
configurations to accommodate the new structure.

[1] https://gem5-review.googlesource.com/c/public/gem5/+/65891

Change-Id: I55fdd383c96286d179724e0f50771e2b5daaa6d7
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/69679
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>
1 file changed