rt2x00: add device id for windy31 usb device

commit 9c4cf6d94fb362c27a24df5223ed6e327eb7279a upstream.

This patch adds the device id for the windy31 USB device to the rt73usb
driver.

Thanks to Ralf Flaxa for reporting this and providing testing and a
sample device.

Reported-by: Ralf Flaxa <rf@suse.de>
Tested-by: Ralf Flaxa <rf@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Acked-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>