USB: ledtrig-usbport: fix of-node leak

This code looks up a USB device node from a given parent USB device but
never dropped its reference to the returned node.

As only the address of the node is used for a later matching, the
reference can be dropped immediately.

Note that this trigger implementation confuses the description of the
USB device connected to a port with the port itself (which does not have
a device-tree representation).

Fixes: 4f04c210d0 ("usb: core: read USB ports from DT in the usbport LED trigger driver")
Cc: Rafał Miłecki <rafal@milecki.pl>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/core/ledtrig-usbport.c

@@ -137,11 +137,17 @@ static bool usbport_trig_port_observed(struct usbport_trig_data *usbport_data,
 	if (!led_np)
 		return false;
 
-	/* Get node of port being added */
+	/*
+	 * Get node of port being added
+	 *
+	 * FIXME: This is really the device node of the connected device
+	 */
 	port_np = usb_of_get_child_node(usb_dev->dev.of_node, port1);
 	if (!port_np)
 		return false;
 
+	of_node_put(port_np);
+
 	/* Amount of trigger sources for this LED */
 	count = of_count_phandle_with_args(led_np, "trigger-sources",
 					   "#trigger-source-cells");