drm/tegra: dc: Add missing of_node_put()

for_each_matching_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 n;
expression e;
@@

 for_each_matching_node(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: Thierry Reding <treding@nvidia.com>