net/mlx4: support multicast address list interface

net/mlx4: support multicast address list interface

Since this driver does not distinguish unicast/multicast addresses,
applications could always rely on the standard MAC add/remove/set
interface to configure both types.

As a result, the multicast address list interface never got implemented
(rte_eth_dev_set_mc_addr_list()) however PMD-agnostic applications still
rely on it for compatibility reasons; a wrapper is therefore required.

Signed-off-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>
Acked-by: Shahaf Shuler <shahafs@mellanox.com>