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

(from https://patchwork.kernel.org/patch/10005409/

)

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.

Bug: 67651285
Bug: 67600404
Change-Id: I9ad5cb137eb627b9fd22740d2ab98e0221433c95
Cc: stable@vger.kernel.org
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>