mlxsw: spectrum_trap: Register layer 3 control traps

In a similar fashion to layer 2 control traps, register layer 3 control
traps with devlink.

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