ofproto-dpif-xlate: Add a drop action for native tunnel failure.

Upon tunnel output failure, due to routing failure for example, add an
explicit drop action, so it will appear in the dp-flows for better
visibility for that case.
For those, add additional drop reasons.

Reviewed-by: Roi Dayan <roid@nvidia.com>
Signed-off-by: Eli Britstein <elibr@nvidia.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>

include/linux/openvswitch.h

@@ -465,6 +465,10 @@ enum xlate_error {
 	XLATE_UNSUPPORTED_PACKET_TYPE,
 	XLATE_CONGESTION_DROP,
 	XLATE_FORWARDING_DISABLED,
+	XLATE_TUNNEL_ROUTING_FAILED,
+	XLATE_TUNNEL_OUTPUT_NO_ETHERNET,
+	XLATE_TUNNEL_NEIGH_CACHE_MISS,
+	XLATE_TUNNEL_HEADER_BUILD_FAILED,
 	XLATE_MAX,
 };
 #endif