nfsd: Remove incorrect check in nfsd4_validate_stateid

nfsd: Remove incorrect check in nfsd4_validate_stateid

If the client is calling TEST_STATEID, then it is because some event
occurred that requires it to check all the stateids for validity and
call FREE_STATEID on the ones that have been revoked. In this case,
either the stateid exists in the list of stateids associated with that
nfs4_client, in which case it should be tested, or it does not. There
are no additional conditions to be considered.

Reported-by: "Frank Ch. Eigler" <fche@redhat.com>
Fixes: 7df302f75ee2 ("NFSD: TEST_STATEID should not return NFS4ERR_STALE_STATEID")
Cc: stable@vger.kernel.org # v5.7+
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>