rt2x00: Add support for BUFFALO WLI-UC-GNM2 to rt2800usb.

commit a769f9577232afe2c754606a83aad85127e7052a upstream.

This is a RT3070 based device.

Signed-off-by: Jeongdo Son <sohn9086@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>