mailbox: Convert to using %pOFn instead of device_node.name

In preparation to remove the node name pointer from struct device_node,
convert printf users to use the %pOFn format specifier.
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

drivers/mailbox/ti-msgmgr.c

@@ -560,8 +560,8 @@ static struct mbox_chan *ti_msgmgr_of_xlate(struct mbox_controller *mbox,
 	}
 
 err:
-	dev_err(inst->dev, "Queue ID %d, Proxy ID %d is wrong on %s\n",
-		req_qid, req_pid, p->np->name);
+	dev_err(inst->dev, "Queue ID %d, Proxy ID %d is wrong on %pOFn\n",
+		req_qid, req_pid, p->np);
 	return ERR_PTR(-ENOENT);
 }