net/mlx4_en: Set statistics bitmap at port init

Port statistics bitmap will now be initialized at port init.  Even before
starting the port, statistics are visible to the user and must be properly masked.

Signed-off-by: Eran Ben Elisha <eranbe@mellanox.com>
Signed-off-by: Hadar Hen Zion <hadarh@mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>