atm: lanai: use kernel's '%pM' format option to print MAC

Signed-off-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Chas Williams <chas@cmf.nrl.navy.mil>
Cc: linux-atm-general@lists.sourceforge.net
Signed-off-by: David S. Miller <davem@davemloft.net>