ftdi_sio: support for Signalyzer tools based on FTDI chips

This patch adds support for the Xverve Signalyzers.
Signed-off-by: Colin Leitner <colin.leitner@googlemail.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>