net/mlx5: Mask destination mac value in ethtool steering rules

We need to mask the destination mac value with the destination mac
mask when adding steering rule via ethtool.

Fixes: 1174fce8 ('net/mlx5e: Support l3/l4 flow type specs in ethtool flow steering')
Signed-off-by: Maor Gottlieb <maorg@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>