Add the new interactive command:
mcast_addr add|remove X <mcast_addr>
to add/remove the multicast MAC address <mcast_addr> to/from the set of
multicast addresses filtered by port <X>.
Command used to test the function "rte_eth_dev_set_mc_addr_list"
that has been added to the API of PMDs.
Signed-off-by: Ivan Boule <ivan.boule@6wind.com>