rt2x00: add USB ID for the Linksys WUSB200.

add USB ID for the Linksys WUSB200 Wireless-G Business USB Adapter to
rt73usb.

Signed-off-by: Stefan Lippers-Hollmann <s.l-h@gmx.de>
Cc: stable <stable@kernel.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>