net: marvell: prestera: define MDB/flood domain entries and HW API to offload them to the HW

Define MDB entry that can be offloaded:
  - FDB entry, that defines an multicast group to which traffic can be
    replicated to;
Define flood domain:
  - Arrangement of ports (list), that have joined multicast group, which
    would receive and replicate to multicast traffic of specified group;
Define flood domain port:
  - single flood domain list entry, that is associated with any given
    bridge port interface (could be LAG interface or physical port-member).
    Applicable to both Q and D bridges;

Co-developed-by: Yevhen Orlov <yevhen.orlov@plvision.eu>
Signed-off-by: Yevhen Orlov <yevhen.orlov@plvision.eu>
Signed-off-by: Oleksandr Mazur <oleksandr.mazur@plvision.eu>
Signed-off-by: David S. Miller <davem@davemloft.net>