net/mlx4_en: Protect MAC address modification with the state_lock mutex

This Patches solves an issue that could raise when modifying the
device's MAC. It occurs due to a simultaneous access to priv->mac_hash
from two contexts. The buggy scenario described below:
Context 1: copy the new mac address to the dev->dev_addr field.
Context 2: mlx4_en_do_uc_filter removes prev_mac entry from the mac_hash
           db since it is not in dev->uc and not equal to dev->dev_addr.
Context 1: mlx4_en_do_set_mac() calls mlx4_en_replace_mac() to replace
           prev_mac with dev_addr but it fails to update the mac_hash db
           since it no longer contains prev_mac, therefore it returns
           with an error.

The fix is to prevent mlx4_en_do_uc_filter from being executed by both
of the context 1 calls described above, This is done by putting them
both under the mdev->state_lock lock, it will solve this issue since
mlx4_en_do_uc_filter is already protected by the mdev->state_lock.

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