Set policy_file in the oslo_policy group

policy_file in DEFAULT is deprecated

Change-Id: I6698a810d5e6c395a18aed8066e61f8c4bae2408
diff --git a/lib/neutron-legacy b/lib/neutron-legacy
index 3072d0a..ac1cd0f 100644
--- a/lib/neutron-legacy
+++ b/lib/neutron-legacy
@@ -1081,7 +1081,7 @@
 
     iniset $NEUTRON_CONF DEFAULT verbose True
     iniset $NEUTRON_CONF DEFAULT debug $ENABLE_DEBUG_LOG_LEVEL
-    iniset $NEUTRON_CONF DEFAULT policy_file $Q_POLICY_FILE
+    iniset $NEUTRON_CONF oslo_policy policy_file $Q_POLICY_FILE
     iniset $NEUTRON_CONF DEFAULT allow_overlapping_ips $Q_ALLOW_OVERLAPPING_IP
 
     iniset $NEUTRON_CONF DEFAULT auth_strategy $Q_AUTH_STRATEGY