vfs_ceph_new: dont use ceph_ll_nonblocking_readv_writev for fsync_send

vfs_ceph_new: dont use ceph_ll_nonblocking_readv_writev for fsync_send

Commit 4ae922413844 ("vfs_ceph_new: use libcephfs nonblocking API for
async-io ops") uses ceph_ll_nonblocking_readv_writev for fsync_send.
However, the actual behaviour of libcephfs when using this API with
'fsync=true' is not async-fsync, as one may assume. Instead,
vfs_ceph_new should use a nonblocking fsync API[1], once it is ready.

Removed the usage of ceph_ll_nonblocking_readv_writev for fsync.

Bug: https://bugzilla.samba.org/show_bug.cgi?id=15919

[1] https://github.com/ceph/ceph/commit/c88a21c30d8b265adb152f631d2629d29539f7b7

Signed-off-by: Shachar Sharon <ssharon@redhat.com>
Reviewed-by: Anoop C S <anoopcs@samba.org>
Reviewed-by: Xavi Hernandez <xhernandez@redhat.com>
Reviewed-by: Guenther Deschner <gd@samba.org>