Skips enabling kernel bridge firewall in container

Calling enable_kernel_bridge_firewall inside a
container, devstack will crash because it tries to
load a kernel module by calling 'sudo modprobe' on
net.bridge.

Change-Id: Id4718c065d5a8c507d49f38e19c2796a64221aa4
Closes-Bug: #1662194
diff --git a/lib/neutron_plugins/ovs_base b/lib/neutron_plugins/ovs_base
index 62a4d00..733a5c1 100644
--- a/lib/neutron_plugins/ovs_base
+++ b/lib/neutron_plugins/ovs_base
@@ -88,7 +88,9 @@
 function _neutron_ovs_base_configure_firewall_driver {
     if [[ "$Q_USE_SECGROUP" == "True" ]]; then
         iniset /$Q_PLUGIN_CONF_FILE securitygroup firewall_driver iptables_hybrid
-        enable_kernel_bridge_firewall
+        if ! running_in_container; then
+            enable_kernel_bridge_firewall
+        fi
     else
         iniset /$Q_PLUGIN_CONF_FILE securitygroup firewall_driver noop
     fi