FatFs: Fix regression reading FAT table.
FatFs: Fix regression reading FAT table.

Need to convert block index to absolute before giving it to BlockCache.

ambrop72/aprinter,johnkingsley/aprinter,fixator/aprinter,fixator/aprinter,johnkingsley/aprinter,ambrop72/aprinter,ambrop72/aprinter,johnkingsley/aprinter,johnkingsley/aprinter,fixator/aprinter,fixator/aprinter,ambrop72/aprinter,ambrop72/aprinter,fixator/aprinter,fixator/aprinter,johnkingsley/aprinter,johnkingsley/aprinter,ambrop72/aprinter,ambrop72/aprinter,johnkingsley/aprinter