nfsd4: purge stable client records with insufficient state

To escape having your stable storage record purged at the end of the
grace period, it's not sufficient to simply have performed a
setclientid_confirm; you also need to meet the same requirements as
someone creating a new record: either you should have done an open or
open reclaim (in the 4.0 case) or a reclaim_complete (in the 4.1 case).

Signed-off-by: J. Bruce Fields <bfields@redhat.com>