[S390] avenrun export in appdata_base.c

Remove EXPORT_SYMBOL_GPL(avenrun) from appdata_base.c, since it is
already exported in kernel/timer.c

Signed-off-by: Gerald Schaefer <geraldsc@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>