It is now required that all changes to max_mds use the run-time `ceph fs
set max_mds` command. The rationale for this change is that it is
confusing to have a configuration for max_mds which is only observed at
file system creation.
Fixes: http://tracker.ceph.com/issues/17105
Signed-off-by: Patrick Donnelly <pdonnell@redhat.com>
