mlxsw: spectrum_fid: Make mlxsw_sp_fid_ops.setup return an int

This operation will be fallible for rFIDs in CFF mode, which will be
introduced in follow-up patches. Have it return an int, and handle
the failures in the caller.

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/75f1b85c0cb86bea5501fcc8657042f221a78b32.1701183892.git.petrm@nvidia.com


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