USB: ti_usb_3410_5052: adding multitech dialup fax/modem devices

The following patch adds support for Multitech Systems' MT9234MU and
MT9234ZBA usb dialup fax modems. It is based on a patch and firmware
provided to me by Multitech Systems' support, after I reported to them
that my MT9234MU modem was not working with recent linux kernels.

Signed-off-by: Alex Manoussakis <alex@juniper.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>