userspace: Add OXM field MFF_PACKET_TYPE

Allow packet type namespace OFPHTN_ETHERTYPE as alternative pre-requisite
for matching L3 protocols (MPLS, IP, IPv6, ARP etc).

Change the meta-flow definition of packet_type field to use the new
custom format MFS_PACKET_TYPE representing "(NS,NS_TYPE)".

Parsing routine for MFS_PACKET_TYPE added to meta-flow.c. Formatting
routine for field packet_type extracted from match_format() and moved to
flow.c to be used from meta-flow.c for formatting MFS_PACKET_TYPE.

Updated the ovs-fields man page source meta-flow.xml with documentation
for packet-type-aware bridges and added documentation for field packet_type.

Added packet_type to the matching properties in tests/ofproto.at.

If dl_type is unwildcarded due to later packet modification, make sure it
is cleared again if the original packet_type was not PT_ETH.

Signed-off-by: Jan Scheurich <jan.scheurich@ericsson.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>

lib/learn.c

@@ -139,6 +139,7 @@ learn_execute(const struct ofpact_learn *learn, const struct flow *flow,
         switch (spec->dst_type) {
         case NX_LEARN_DST_MATCH:
             mf_write_subfield(&spec->dst, &value, &fm->match);
+            match_add_ethernet_prereq(&fm->match, spec->dst.field);
             mf_vl_mff_set_tlv_bitmap(
                 spec->dst.field, &fm->match.flow.tunnel.metadata.present.map);
             break;