net/mlx4_en: current_mac isn't updated in port up

When port is down dev_addr is changed (e.g. by bonding) but current_mac
is not touched. When port is up again, hash_mac is updated to dev_addr,
but current_mac isn't. This leads to inconsistency between current_mac
and mac_hash. Because of that, mlx4_en_replace_mac() fails to find
current_mac in mac_hash.

Fix is to reset current_mac to dev_addr when port is up - as we do for
mac_hash.

Signed-off-by: Eyal Perry <eyalpe@mellanox.com>
Signed-off-by: Amir Vadai <amirv@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>