RFC5661 obsoletes NFS4ERR_STALE_STATEID in favour of NFS4ERR_BAD_STATEID.

Note that because nfsd encodes the clientid boot time in the stateid, we
can hit this error case in certain scenarios where the Linux client
state management thread exits early, before it has finished recovering
all state.
Reported-by: NIdan Kedar <idank@primarydata.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>