IB/mlx4: Reuse mlx4_mac_to_u64()

This function is implemented twice... get rid of one copy.

Signed-off-by: Moni Shoua <monis@mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>