rt2800usb: add usb ID 1b75:3070 for Airlive WT-2000USB

Brand: Airlive (Ovislink Corp.)
Name: Turbo-G USB Adaptor
Model: WT-2000USB
USB ID: 1b75:3070

Reported-and-tested-by: Michael Coates <michlinux@hotmail.com>
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>