sd-image: Do not use batch operation for `mcopy`.

```
       b      Batch mode. Optimized for huge recursive copies, but less secure if a crash happens during the copy.
```

It seems the "less secure if a crash happens" does not need a crash to
happen.

With batch mode:

```
/[...]/.
  Start (0) does not point to parent (___)
```

For pretty much everything copied in.

Without batch mode, everything passes `fsck`.

See #51150