mlxsw: spectrum_fid: Add hooks for RSP table maintenance

mlxsw: spectrum_fid: Add hooks for RSP table maintenance

In the CFF flood mode, the driver has to allocate a table within PGT, which
holds flood vectors for router subport FIDs. For LAGs, these flood vectors
have to obviously be maintained dynamically as port membership in a LAG
changes. But even for physical ports, the flood vectors have to be kept
valid, and may not contain enabled bits corresponding to non-existent
ports. It is therefore not possible to precompute the port part of the RSP
table, it has to be maintained as ports come and go due to splits.

To support the RSP table maintenance, add to FID ops two new ops:
fid_port_init and fid_port_fini, for when a port comes to existence, or
joins a lag, and vice versa. Invoke these ops from
mlxsw_sp_port_fids_init() and mlxsw_sp_port_fids_fini(), which are called
when port is added and removed, respectively. Also add two new hooks for
LAG maintenance, mlxsw_sp_fid_port_join_lag() / _leave_lag() which
transitively call into the same ops.

Later patches will actually add the op implementations themselves, this
just adds the scaffolding.

Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Amit Cohen <amcohen@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://lore.kernel.org/r/234398a23540317abb25f74f920a5c8121faecf0.1701183892.git.petrm@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>