[S390] Fix section annotations.

Use the __cpuinit instead of __devinit section annotations for code
that deals with cpu hotplug. In addition add some more annotations on
functions that have been left out so far.

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