mlxsw: spectrum_router: Call RIF setup before obtaining FID

For subport RIFs, the setup initializes, among other things, RIF port and
LAG numbers. Those are important to determine where in the PGT the RIF FID
will be stored. Therefore, call the RIF setup before fid_get.

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/f24d8cad7e4748b8e8e0e16894ca6a20704dea32.1700503644.git.petrm@nvidia.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>