USB: ftdi_sio: fix initial baud rate

Fix regression introduced by commit b1ffb4c8 ("USB: Fix Corruption
issue in USB ftdi driver ftdi_sio.c") which caused the termios settings
to no longer be initialised at open. Consequently it was no longer
possible to set the port to the default speed of 9600 baud without first
changing to another baud rate and back again.

Reported-by: Roland Ramthun <mail@roland-ramthun.de>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Tested-by: Roland Ramthun <mail@roland-ramthun.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>