wireless: ray_cs: use '%pm' format option to print MAC

Signed-off-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: "John W. Linville" <linville@tuxdriver.com>
Cc: linux-wireless@vger.kernel.org
Signed-off-by: John W. Linville <linville@tuxdriver.com>