Staging: add USB serial Quatech driver

Add support for all Quatech usb to serial devices.

Based on an original driver from Quatech.

Cleaned up and forward ported by me.

It's a mess, uses it's own tty layer interface, and the coding style is
horrible.

Cc: Tim Gobeli <tgobeli@quatech.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>