Comment out fsck for FAT label test
Comment out fsck for FAT label test

The FAT label is still tested using `mdir`, but due to an update to
dosfstools, fsck fails now and can't be used for this until the FatFS
library is updated. The failure is due to the disk label in the FAT
filesystem header is different than the special directory file that
contains the label. This does not appear to have any bad effects other
than causing the dosfstools 4.2 fsck to fail. Consequently comment out
this check for now.

fhunleth/fwup,fhunleth/fwup,fhunleth/fwup