Explicitly select "HT40-" for 5GHz HT40 tests

server/site_tests/network_WiFiPerf/071Perf5HT40PS

 # 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.
 
 # Test performance of an open 802.11n/HT40 connection in the 5GHz band
 # w/ power save enabled.
 
 # TODO(sleffler) expand channel coverage
 
 { "name":"Perf5HT40_PS",
   "steps":[             # Channel 48
     [ "create",         { "type":"hostap" } ],
-    [ "config",         { "channel":"5240", "ht40":None, "puren":None } ],
+    [ "config",         { "channel":"5240", "ht40-":None, "puren":None } ],
     [ "connect",        { "security":"none" } ],
 
     [ "client_powersave_on" ],
 
     [ "client_iperf",   { "tcp":None, "test_time":"60" } ],
     [ "server_iperf",   { "tcp":None, "test_time":"60" } ],
 
     [ "client_iperf",   { "udp":None, "bandwidth":"10m" } ],
     [ "server_iperf",   { "udp":None, "bandwidth":"10m" } ],
 
@@ skipping 26 matching lines @@
 
     [ "client_iperf",   { "udp":None, "bandwidth":"110m" } ],
     [ "server_iperf",   { "udp":None, "bandwidth":"110m" } ],
 
     [ "client_iperf",   { "udp":None, "bandwidth":"120m" } ],
     [ "server_iperf",   { "udp":None, "bandwidth":"120m" } ],
 
     [ "destroy" ],
   ],
 }