drivers/macintosh: Delete an unnecessary check before the function call "of_node_put"

The of_node_put() function tests whether its argument is NULL and then
returns immediately. Thus the test around the call is not needed.

This issue was detected by using the Coccinelle software.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

drivers/macintosh/smu.c

@@ -557,7 +557,6 @@ int __init smu_init (void)
 	return 0;
 
 fail_msg_node:
-	if (smu->msg_node)
 	of_node_put(smu->msg_node);
 fail_db_node:
 	of_node_put(smu->db_node);