nfsd: don't run get_file if nfs4_preprocess_stateid_op return error

commit b022032e upstream.

we should return error status directly when nfs4_preprocess_stateid_op
return error.

Signed-off-by: fanchaoting <fanchaoting@cn.fujitsu.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>