nfs: Initialize cb_sequenceres information before validate_seqid()

For a cb_layoutrecall replay, nfsd got CB_SEQUENCE status of zero,
but all informations of cb_sequenceres are zero too !!!

validate_seqid() return NFS4ERR_RETRY_UNCACHED_REP for a replay,
and skip the initlize cb_sequenceres.

Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>