[S390] appldata_base: Misc cpuinit annotations and bugfix

appldata_offline_cpu() is only called from __cpuinit-marked hotplug
notifier callback and from the __exit-marked module_exit function,
therefore candidate for __cpuexit.

BTW the __exit module_exit function appldata_exit() of this driver fails to
unregister_hotcpu_notifier() the notifier_block that was registered by
appldata_init() during module startup.  This will lead to oops if hotplug
notification comes after module has been unloaded.  Let's fix this by
unregistering the notifier appropriately (before appldata_offline_cpu()'ing
the CPUs).

Signed-off-by: Satyam Sharma <satyam@infradead.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>