mlxsw: spectrum: Add NVE packet traps

mlxsw: spectrum: Add NVE packet traps

The DECAP_ECN0 trap will be used to trap packets where the overlay
packet is marked with Non-ECT, but the underlay packet is marked with
either ECT(0), ECT(1) or CE. When trapped, such packets will be counted
as errors by the VxLAN driver and thus provide better visibility.

The NVE_ENCAP_ARP trap will be used to trap ARP packets undergoing NVE
encapsulation. This is needed in order to support E-VPN ARP suppression,
where the Linux bridge does not flood ARP packets through tunnel ports
in case it can answer the ARP request itself.

Note that all the packets trapped via these traps are marked with
'offload_fwd_mark', so as to not be re-flooded by the Linux bridge
through the ASIC ports.

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