f2fs: trigger normal fsync for non-atomic_write file

If file was not opened with atomic write mode, but user uses atomic write
ioctl to fsync datas, in the flow, we should not fsync that file with
atomic write mode.

Fixes: 608514deba38 ("f2fs: set fsync mark only for the last dnode")
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>