macb: convert printk to netdev_ and friends

macb is already using the dev_dbg() and friends helpers so use netdev_()
along with a pr_fmt() definition to make the printing a little cleaner.

Acked-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Jamie Iles <jamie@jamieiles.com>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Tested-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>