USB: ftdi_sio: Added PID for new ekey device

Added support to the ftdi_sio driver for ekey Converter USB which
uses an FT232BM chip.

Signed-off-by: Jaša Bartelj <jasa.bartelj@gmail.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>