powerpc/via-pmu-led.c: Add of_node_put to avoid memory leak

Add a call to of_node_put in the error handling code following a call to
of_find_node_by_path.

The semantic match that finds this problem is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@r exists@
local idexpression x;
expression E,E1;
statement S;
@@

*x =
(of_find_node_by_path
|of_find_node_by_name
|of_find_node_by_phandle
|of_get_parent
|of_get_next_parent
|of_get_next_child
|of_find_compatible_node
|of_match_node
)(...);
...
if (x == NULL) S
<... when != x = E
*if (...) {
  ... when != of_node_put(x)
      when != if (...) { ... of_node_put(x); ... }
(
  return <+...x...+>;
|
*  return ...;
)
}
...>
of_node_put(x);
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

drivers/macintosh/via-pmu-led.c

@@ -92,8 +92,10 @@ static int __init via_pmu_led_init(void)
 	if (dt == NULL)
 		return -ENODEV;
 	model = of_get_property(dt, "model", NULL);
-	if (model == NULL)
+	if (model == NULL) {
+		of_node_put(dt);
 		return -ENODEV;
+	}
 	if (strncmp(model, "PowerBook", strlen("PowerBook")) != 0 &&
 	    strncmp(model, "iBook", strlen("iBook")) != 0 &&
 	    strcmp(model, "PowerMac7,2") != 0 &&