f2fs: expose some sectors to user in inline data or dentry case

If there's some data written through inline data or dentry, we need to shouw
st_blocks. This fixes reporting zero blocks even though there is small written
data.

Cc: stable@vger.kernel.org
Reviewed-by: Chao Yu <yuchao0@huawei.com>
[Jaegeuk Kim: avoid link file for quotacheck]
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>