USB: io_ti: Digi EdgePort update for new devices

This patch adds support for the most recent Digi EdgePort USB serial
devices.

Signed-off-by: Martin K. Petersen <mkp@mkp.net>
Signed-off-by: Mike Swift <mikes@digi.com>
Signed-off-by: Jeremy McBane <jmcbane@digi.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>