mlxsw: spectrum: Add VRRP traps

Virtual Router Redundancy Protocol packets are used to communicate the
state of the Master router associated with the virtual router ID (VRID).

These are link-local multicast packets sent with IP protocol 112 that
are trapped in the router block in the ASIC.

Add a trap for these packets and mark the trapped packets to prevent
them from potentially being re-flooded by the bridge driver.

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