[S390] topology: use default MC domain initializer

Use default MC sched domain initializer, since performance meassurements
finally showed that this is indeed better.
Besides the fact that the powersavings flags functions didn't make too
much sense, but were unused anyway.

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