Use lowercase section name in Neutron ML2 security group config

All other security group configs in Neutron are lower-case
and it should be consistent.

Change-Id: I683333c1e186446a69172446cca6d9b952673ed4
Closes-Bug: #1279862
diff --git a/lib/neutron_plugins/ml2 b/lib/neutron_plugins/ml2
index ab4e347..4ceabe7 100644
--- a/lib/neutron_plugins/ml2
+++ b/lib/neutron_plugins/ml2
@@ -93,9 +93,9 @@
     # instead use its own config variable to indicate whether security
     # groups is enabled, and that will need to be set here instead.
     if [[ "$Q_USE_SECGROUP" == "True" ]]; then
-        iniset /$Q_PLUGIN_CONF_FILE SECURITYGROUP firewall_driver neutron.agent.not.a.real.FirewallDriver
+        iniset /$Q_PLUGIN_CONF_FILE securitygroup firewall_driver neutron.agent.not.a.real.FirewallDriver
     else
-        iniset /$Q_PLUGIN_CONF_FILE SECURITYGROUP firewall_driver neutron.agent.firewall.NoopFirewallDriver
+        iniset /$Q_PLUGIN_CONF_FILE securitygroup firewall_driver neutron.agent.firewall.NoopFirewallDriver
     fi
 
     # Since we enable the tunnel TypeDrivers, also enable a local_ip