s390: Use generic time config

Signed-off-by: Anna-Maria Gleixner <anna-maria@glx-um.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Link: http://lkml.kernel.org/r/20120518163106.595607369@glx-um.de


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>