Remove bridge-utils/brctl usage

This package isn't available on some distributions hasn't been
required in Neutron for several years
If679e79fa3242ee1cd8610b5525deca35b41c87e.  Remove it.

Change-Id: I7308a885c1d084efe2f0b9f542443d35966140ed
diff --git a/lib/neutron_plugins/linuxbridge_agent b/lib/neutron_plugins/linuxbridge_agent
index 1f1b0e8..bdeaf0f 100644
--- a/lib/neutron_plugins/linuxbridge_agent
+++ b/lib/neutron_plugins/linuxbridge_agent
@@ -38,7 +38,7 @@
 }
 
 function neutron_plugin_install_agent_packages {
-    install_package bridge-utils
+    :
 }
 
 function neutron_plugin_configure_dhcp_agent {