linuxbridge: Fix name of securitygroup section

With an incorrectly named section, whatever's defined in here is
actually ignored which can result in unexpected behaviour.

Closes-Bug: 1889455

Change-Id: Ib2e2b53e9a3c0e62a2e997881c0cd1f92acfb39c
Signed-off-by: Nick Jones <nick@dischord.org>

ansible/roles/neutron/templates/linuxbridge_agent.ini.j2

@@ -6,7 +6,7 @@ extensions = {{ neutron_agent_extensions|map(attribute='name')|join(',') }}
 [linux_bridge]
 physical_interface_mappings = physnet1:{{ neutron_external_interface }}
 
-[security_group]
+[securitygroup]
 firewall_driver = neutron.agent.linux.iptables_firewall.IptablesFirewallDriver
 
 [vxlan]

doc/source/reference/networking/neutron.rst

@@ -57,7 +57,7 @@ to using the native OVS firewall driver by employing a configuration override
 
 .. code-block:: ini
 
-   [security_group]
+   [securitygroup]
    firewall_driver = openvswitch
 
 OVN (ml2/ovn)

releasenotes/notes/fix-linuxbridge-secgroups-7e5cae9d630e3db9.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Fixes an issue with the Neutron Linux bridge ML2 driver where the firewall
+    driver configuration was not applied. `LP#1889455
+    <https://launchpad.net/bugs/1889455>`__