ti_usb_3410_5052: add Multi-Tech modem support

Add Multi-Tech cellular modem support to the ti_usb_3410_5052 driver.

Signed-off-by: Chris Adams <cmadams@hiwaay.net>
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>