USB: serial: console: move mutex_unlock() before usb_serial_put()

While in current version there is no use-after-free as USB serial
core holds another reference when the console is registered, we
should better unlock before dropping the reference in
usb_console_setup().

Fixes: 7bd032dc27 ("USB serial: update the console driver")
Signed-off-by: Liang He <windhl@126.com>
Signed-off-by: Johan Hovold <johan@kernel.org>

drivers/usb/serial/console.c

@@ -189,8 +189,8 @@ static int usb_console_setup(struct console *co, char *options)
 	info->port = NULL;
 	usb_autopm_put_interface(serial->interface);
  error_get_interface:
-	usb_serial_put(serial);
 	mutex_unlock(&serial->disc_mutex);
+	usb_serial_put(serial);
 	return retval;
 }