NFSv4: nfs4_locku_done must release the sequence id

commit 2b1bc308f492589f7d49012ed24561534ea2be8c upstream.

If the state recovery machinery is triggered by the call to
nfs4_async_handle_error() then we can deadlock.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>