Updated openstack/openstack
Project: openstack/neutron  555ba34bf09b87e9fbc4b07a28f8aefdbf3cbc08

update ml2_migration to reflect optional methods

This change conditionally executes the schema methods for versions that
support them.

Change-Id: I8a51ac04e62dfcfe1e0a2e69a17664d154f0d1d7
Closes-Bug: #1378732