rt73usb: add WLI-U2-H54HP

Signed-off-by: Kenichi HORIO <moattailk1@gmail.com>
Acked-by: Gertjan van Wingerde <gwingerde@gmail.com>
Acked-by: Ivo van Doorn <ivdoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>