lockdep: do not initialize if already started

If we have already registered a cct for lockdep, do not accept another one.
We already check that the cct matches when we shut down.  This we will run
for the life span of a single cct and no longer.

Fixes: #7965
Signed-off-by: Sage Weil <sage@inktank.com>
lockdep: reset state on shutdown

If we shut down, clear out all of the lockdep state.  This ensures that if
we start up again on another cct, we will not be confused by old type ids
and dependency state.

Possibly contributed to #7965.

Signed-off-by: Sage Weil <sage@inktank.com>
Merge pull request #1592 from ceph/wip-7965

lockdep: fix when instantiated multiple times (bug 7965)

Reviewed-by: Josh Durgin <josh.durgin@inktank.com>