seLinux relabelling breaks (times out) on large filesystems, and
doesn't work with cephfs ReadWriteMany volumes (last relabel wins).

See also https://github.com/kubernetes/kubernetes/blob/02cca1f11a8ae570369540564604d0cde06e0720/pkg/volume/cephfs/cephfs.go#L209



Fixes #2177
Signed-off-by: Angus Lees <gus@inodes.org>