of/unittest: add missing of_node_put

for_each_child_of_node performs an of_node_get on each iteration, so
a break out of the loop requires an of_node_put.

A simplified version of the semantic patch that fixes this problem is as
follows (http://coccinelle.lip6.fr):

// <smpl>
@@
expression root,e;
local idexpression child;
@@

 for_each_child_of_node(root, child) {
   ... when != of_node_put(child)
       when != e = child
(
   return child;
|
+  of_node_put(child);
?  return ...;
)
   ...
 }
// </smpl>

Combine the puts into code at the end of the function, for conciseness.
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Rob Herring <robh@kernel.org>

drivers/of/unittest.c

@@ -205,16 +205,20 @@ static int __init of_unittest_check_node_linkage(struct device_node *np)
 		if (child->parent != np) {
 			pr_err("Child node %s links to wrong parent %s\n",
 				 child->name, np->name);
-			return -EINVAL;
+			rc = -EINVAL;
+			goto put_child;
 		}
 
 		rc = of_unittest_check_node_linkage(child);
 		if (rc < 0)
-			return rc;
+			goto put_child;
 		count += rc;
 	}
 
 	return count + 1;
+put_child:
+	of_node_put(child);
+	return rc;
 }
 
 static void __init of_unittest_check_tree_linkage(void)