mlxsw: spectrum_router: Configure matching local routes for NVE decap

When a local route that matches the source IP of an offloaded NVE tunnel
is notified, the driver needs to program it to perform NVE decapsulation
instead of merely trapping packets to the CPU.

This patch complements "mlxsw: spectrum_router: Enable local routes
promotion to perform NVE decap" where existing local routes were
promoted to perform NVE decapsulation.

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