Staging: rt2870: Add USB ID for Buffalo Airstation WLI-UC-GN

BugLink: http://bugs.launchpad.net/bugs/441990

This was tested to successfully enable the hardware.

Signed-off-by: John Tapsell <johnflux@gmail.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
CC: stable@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>