Use the %pM kernel extension to display the MAC address.

The only difference in the output is that the MAC address is
shown in the usual colon-separated hex notation.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: David S. Miller <davem@davemloft.net>