net/mac89x0: Fix and modernize log messages

Fix log message fragments that no longer produce the desired output
since the behaviour of printk() was changed.
Add missing printk severity levels.
Drop deprecated "out of memory" message as per checkpatch advice.

Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>