[S390] cpu topology: dont destroy cpu sets on topology change

Call rebuild_sched_domains instead of arch_reinit_sched_domains if
cpu topology changes. This leaves cpu sets alone which otherwise would
be destroyed.
If and how it makes sense to define cpu sets on a virtualized
architecture is another question.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kernel/topology.c

@@ -12,6 +12,7 @@
 #include <linux/workqueue.h>
 #include <linux/cpu.h>
 #include <linux/smp.h>
+#include <linux/cpuset.h>
 #include <asm/delay.h>
 #include <asm/s390_ext.h>
 #include <asm/sysinfo.h>
@@ -234,7 +235,7 @@ void arch_update_cpu_topology(void)
 
 static void topology_work_fn(struct work_struct *work)
 {
-	arch_reinit_sched_domains();
+	rebuild_sched_domains();
 }
 
 void topology_schedule_update(void)