cpumask: replace node_to_cpumask with cpumask_of_node.

Impact: cleanup

node_to_cpumask (and the blecherous node_to_cpumask_ptr which
contained a declaration) are replaced now everyone implements
cpumask_of_node.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/include/linux/topology.h b/include/linux/topology.h
index a16b9e0..16b7d68 100644
--- a/include/linux/topology.h
+++ b/include/linux/topology.h
@@ -38,11 +38,7 @@
 #endif
 
 #ifndef nr_cpus_node
-#define nr_cpus_node(node)				\
-	({						\
-		node_to_cpumask_ptr(__tmp__, node);	\
-		cpus_weight(*__tmp__);			\
-	})
+#define nr_cpus_node(node) cpumask_weight(cpumask_of_node(node))
 #endif
 
 #define for_each_node_with_cpus(node)			\