ext2fs: 'struct ufid': Re-order fields and unpack

[olce]

Summary

Re-ordering the fields suppresses the trailing padding which was causing
the structure to overflow 'struct fid'.

While here, re-indent in a more visually pleasing way.

[rmacklem]

Looks fine to me.

[emaste]

Yes ext2fs conveniently has a 32-bit field that can be relocated so we can avoid __packed.