arm, config: Fix CPU names in ARM example configs

arm, config: Fix CPU names in ARM example configs

The ARM example configs used to rely on CPU aliases for the
AtomicSimpleCPU and KVM when configuring clusters. This broken when
support for CPU aliases was removed ('config: Remove support for CPU
aliases.'). This change updates the config scripts to use the full
class names instead.

Change-Id: If36c46207f39ca1897ecf77d9588f1c059819e63
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/4360
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>