USB: ftdi_sio: remove redundant raise of DTR/RTS at open

Do not raise DTR/RTS a second time in set_termios at open -- this has
already been taken care of by the tty layer.

Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>