Make logging of an ethernet address more consistent with
the rest of the kernel.

Miscellanea:

The %02hx use also did not quite match the u8 definition
of addr though that did not actually matter given normal
integer promotion rules.
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>