Explicitly select "HT40-" for 5GHz HT40 tests

server/site_tests/network_WiFiMatFunc/071Perf5HT40

 # Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 { "name":"Perf5HT40",
   "steps":[             # Channel 48
     [ "create",         { "type":"hostap" } ],
 
-    [ "config",         { "channel":"5240", "ht40":None, "puren":None } ],
+    [ "config",         { "channel":"5240", "ht40-":None, "puren":None } ],
     [ "client_powersave_off" ],
     [ "connect",        { "security":"none" } ],
     [ "client_iperf",   { "udp":None, "bandwidth":"220m" } ],
     [ "server_iperf",   { "udp":None, "bandwidth":"220m" } ],
     [ "client_iperf",   { "tcp":None } ],
     [ "server_iperf",   { "tcp":None } ],
     # XXX multiple streams
     # XXX mixed streams
     [ "deconfig" ],
 
     [ "destroy" ],
   ],
 }