drivers/infiniband/hw/cxgb3/iwch_cm.c: use %pM to show MAC address

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>
Acked-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: David S. Miller <davem@davemloft.net>