NFC: port100: Fix device leak

port100_probe() calls usb_get_dev(), but there is no usb_put_dev()
in port100_disconnect(). The patch adds one.

Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

drivers/nfc/port100.c

@@ -1509,6 +1509,7 @@ static void port100_disconnect(struct usb_interface *interface)
 
 	usb_free_urb(dev->in_urb);
 	usb_free_urb(dev->out_urb);
+	usb_put_dev(dev->udev);
 
 	kfree(dev->cmd);