[ovsp4rt] Prepare[V6]TunnelTermTableEntry adds undefined match key field

[ffoulkes]

The ES2K variant of the PrepareTunnelTermTableEntry() function adds a match field for the Bridge ID (user_meta.pmeta.bridge_id).

  match->set_field_id(GetMatchFieldId(p4info, IPV4_TUNNEL_TERM_TABLE,
                                      IPV4_TUNNEL_TERM_TABLE_KEY_BRIDGE_ID));
  match->mutable_exact()->set_value(EncodeByteValue(1, tunnel_info.bridge_id));

The Linux Networking P4 program does not define this match field for ipv4_tunnel_term_table.

As a result, the TableEntry contains a match_field with an ID of -1 (maxint when rendered as an unsigned integer).

  {
   "field_id": 4294967295,
   "exact": {
    "value": "Vg=="
   }
  },

PrepareV6TunnelTermTableEntry() has the same problem.