mlxsw: spectrum_trap: Allow for per-ASIC trap groups initialization

Subsequent patches will need to register different trap groups for
Spectrum-1 and Spectrum-2 onwards.

Enable that by invoking a per-ASIC operation during trap groups
initialization.

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