sched: add arch_update_cpu_topology hook.

Will be called each time the scheduling domains are rebuild.
Needed for architectures that don't have a static cpu topology.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/linux/topology.h b/include/linux/topology.h
index 2d8dac8..bd14f8b 100644
--- a/include/linux/topology.h
+++ b/include/linux/topology.h
@@ -50,6 +50,8 @@
 	for_each_online_node(node)						\
 		if (nr_cpus_node(node))
 
+void arch_update_cpu_topology(void);
+
 /* Conform to ACPI 2.0 SLIT distance definitions */
 #define LOCAL_DISTANCE		10
 #define REMOTE_DISTANCE		20