Free cluster chain error results in disk leakage

[stayclean]

In free cluster chain func:
two mistakes:
1.
fat_entry starts from FAT[cluster], and in the while loop, the fat_entry is updated again before set FAT[cluster] to 0x0, thus cause the FAT[cluster] not dereferenced.
2.
The last eoc in fat not been released!

This cause 2 clusters leakage in a single free cluster call.