netdev/phy: add missing of_node_put

for_each_available_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>
@@
local idexpression r.n;
expression r,e;
@@

 for_each_available_child_of_node(r,n) {
   ...
(
   of_node_put(n);
|
   e = n
|
+  of_node_put(n);
?  break;
)
   ...
 }
... when != n
// </smpl>

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/mdio-mux.c

@@ -144,6 +144,7 @@ int mdio_mux_init(struct device *dev,
 			dev_err(dev,
 				"Error: Failed to allocate memory for child\n");
 			ret_val = -ENOMEM;
+			of_node_put(child_bus_node);
 			break;
 		}
 		cb->bus_number = v;