message: nydus-image: set blocks of superblock
  Set rafs v6's blocks of superblock to a non-zero value.
diff: @@ -568,7 +568,7 @@ impl Bootstrap {
  let mut sb = RafsV6SuperBlock::new();
  sb.set_inos(bootstrap_ctx.nodes.len() as u64);
  // FIXME
  - sb.set_blocks(0);
  + sb.set_blocks(EROFS_BLOCK_SIZE as u32);
  sb.set_root_nid(root_nid as u16);
  sb.set_meta_addr(meta_addr);
  