mlxsw: spectrum_fid: Configure layer 3 egress VID classification

After routing, the device always consults a table that determines the
packet's egress VID based on {egress RIF, egress local port}. In the
unified bridge model, it is up to software to maintain this table via REIV
register.

The table needs to be updated in the following flows:
1. When a RIF is set on a FID, need to iterate over the FID's {Port, VID}
   list and issue REIV write to map the {RIF, Port} to the given VID.
2. When a {Port, VID} is mapped to a FID and the FID already has a RIF,
   need to issue REIV write with a single record to map the {RIF, Port}
   to the given VID.

REIV register supports a simultaneous update of 256 ports, so use this
capability for the first flow.

Handle the two above mentioned flows.

Add mlxsw_sp_fid_evid_map() function to handle egress VID classification
for both unicast and multicast. Layer 2 multicast configuration is already
done in the driver, just move it to the new function.

Signed-off-by: Amit Cohen <amcohen@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>