s390/topology: reduce per_cpu() invocations

Each per_cpu() invocation generates extra code. Since there are a lot
of similiar calls in the topology code we can avoid a lot of them.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>