f2fs: trigger fdatasync for non-atomic_write file

Sqlite only cares about synchronization of file data instead of other data
unrelated attribute of inode, so in commit flow, call fdatasync is enough.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>