DM9000: Update and fix driver debugging messages

There was a missing newline in a dev_dbg() message.  Values read
from/written into PHY registers might be for interest too, so I added
new dbg messages there.

Signed-off-by: Enrico Scholz <enrico.scholz@sigma-chemnitz.de>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>