Remove private zombie flag used to signal disconnect and to prevent
control urb from being submitted from interrupt urb completion handler.

The control urb will not be re-submitted as both the control urb and the
interrupt urb is killed on disconnect.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>