cpu: Remove reduntant protobuf includes

Change-Id: Ic34b94b3a2ea951bc023cfce2d09ce304a602e41
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/11512
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
12 files changed