hfsplus: change finder_info to u32

The finder_info block in the hfsplus volume header is currently defined as
an array of 8 bit values, but TN1150 defines it as being an array of 32 bit
values. Fix for convenience.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>