USB: ftdi-sio: Add support for RT Systems USB-RTS01 serial adapter

Add support for RT Systems USB-RTS01 USB to Serial adapter:
http://www.rtsystemsinc.com/Photos/USBRTS01.html

Tested by controlling Icom IC-718 amateur radio transceiver via hamlib.

Signed-off-by: Evan McNabb <evan@mcnabbs.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>