staging: vt6656: use %pM for the BSSID

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Marcos Paulo de Souza <marcos.souza.org@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>