powerpc/windfarm: Use for_each_node_by_type() macro

Use for_each_node_by_type() macro instead of open coding it.

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/drivers/macintosh/windfarm_rm31.c b/drivers/macintosh/windfarm_rm31.c
index 844003f..0b9a79b 100644
--- a/drivers/macintosh/windfarm_rm31.c
+++ b/drivers/macintosh/windfarm_rm31.c
@@ -696,7 +696,7 @@
 
 	/* Count the number of CPU cores */
 	nr_chips = 0;
-	for (cpu = NULL; (cpu = of_find_node_by_type(cpu, "cpu")) != NULL; )
+	for_each_node_by_type(cpu, "cpu")
 		++nr_chips;
 	if (nr_chips > NR_CHIPS)
 		nr_chips = NR_CHIPS;