As part of change I1826f2970528928a31b32a664013380e38bbd7c9
we added a configuration option to the manila cephfs nfs driver
when deployed using cephadm.
We also need this option set here to get the m-shr service
to pick the right helper when deploying with DevStack
Change-Id: If99714e07f4b75c76db29a660ad8d1e93f7055e5