drm: rcar-du: add missing of_node_put

Add an of_node_put when the result of of_graph_get_remote_port_parent is
not available.

Add a second of_node_put if no encoder is selected (encoder remains NULL).

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

// <smpl>
@r exists@
local idexpression e;
expression x;
@@
e = of_graph_get_remote_port_parent(...);
... when != x = e
    when != true e == NULL
    when != of_node_put(e)
    when != of_fwnode_handle(e)
(
return e;
|
*return ...;
)
// </smpl>

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

drivers/gpu/drm/rcar-du/rcar_du_kms.c

@@ -352,6 +352,7 @@ static int rcar_du_encoders_init_one(struct rcar_du_device *rcdu,
 		dev_dbg(rcdu->dev,
 			"connected entity %pOF is disabled, skipping\n",
 			entity);
+		of_node_put(entity);
 		return -ENODEV;
 	}
 
@@ -387,6 +388,7 @@ static int rcar_du_encoders_init_one(struct rcar_du_device *rcdu,
 		dev_warn(rcdu->dev,
 			 "no encoder found for endpoint %pOF, skipping\n",
 			 ep->local_node);
+		of_node_put(entity);
 		return -ENODEV;
 	}