SUNRPC: 'Directory with parent 'rpc_clnt' already present!'

SUNRPC: 'Directory with parent 'rpc_clnt' already present!'

Each rpc_client has a cl_clid which is allocated from a global ida, and
a debugfs directory which is named after cl_clid.

We're releasing the cl_clid before we free the debugfs directory named
after it.  As soon as the cl_clid is released, that value is available
for another newly created client.

That leaves a window where another client may attempt to create a new
debugfs directory with the same name as the not-yet-deleted debugfs
directory from the dying client.  Symptoms are log messages like

	Directory 4 with parent 'rpc_clnt' already present!

Fixes: 7c4310ff5642 "SUNRPC: defer slow parts of rpc_free_client() to a workqueue."
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>