USB: Add device id for Sierra Wireless MC8755

Adds the device id used by the UMTS cards in Lenovo X60s notebooks sold
in Europe.

Signed-off-by: Jan Luebbe <jluebbe@lasnet.de>
Cc: Kevin Lloyd <linux@sierrawireless.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>