cluster_count is compared against FAT16_MAX, which is defined as 0xfff4
That is the maximum number of cluster a FAT16 can have.
For reference also check the hardware whitepaper from Microsoft
FAT: General Overview of On-Disk Format, version 1.03 page 15
Signed-off-by: Thomas Frauendorfer <tf@miray.de>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>