net/mlx5: Enable MACsec offload feature for VLAN interface

Enable MACsec offload feature over VLAN by adding NETIF_F_HW_MACSEC
to the device vlan_features.

Signed-off-by: Emeel Hakim <ehakim@nvidia.com>
Reviewed-by: Subbaraya Sundeep <sbhatta@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>