ethernet: 8390: remove direct netdev->dev_addr writes

8390 contains a lot of loops assigning netdev->dev_addr
byte by byte. Convert what's possible directly to
eth_hw_addr_set(), use local buf in other places.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>