mlxsw: spectrum: Set RIF ops per ASIC type

Set RIF ops array as member of mlxsw_sp in order to control which RIF
operations callbacks are called per ASIC type. This is needed to control
per ASIC handling of loopback RIF configurations.

Signed-off-by: Nir Dotan <nird@mellanox.com>
Reviewed-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>