USB: sierra driver - add devices

The following improvements were made:
 - Added new product support: MC5725, AC 880 U, MP 3G (UMTS & CDMA)

Cc: stable <stable@kernel.org>
Signed-off-by: Kevin Lloyd <linux@sierrawireless.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>