staging: r8188eu: Fix skb leak in usb_read_port_complete()

In the completion routine for a usb_fill_bulk_urb() call, an skb is
leaked whenever the status of the USB transaction is not zero. A call
to skb_put() is needed to fix the problem.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>