mds: Make SimpleLock wait shift bits unique like they should be.
mds: Make SimpleLock wait shift bits unique like they should be.

This wasn't actually breaking stuff before, but it did mean
we woke up stuff we didn't need to.

ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph