migration: fix duplicate initialization for expected_downtime and cleanup_bh

migrate_fd_connect duplicate initialize expected_downtime and cleanup_bh.

Signed-off-by: Lidong Chen <lidongchen@tencent.com>
Message-Id: <1532434585-14732-2-git-send-email-lidongchen@tencent.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>