Kernel install image is broken on VFAT images since it unmounts directory in preinstall and doesn't mount back. We used to have this for NAND / FAT install which fixes this in the postinst script. Removing since we have no more support for NAND anyway. Tested on Odroid C1. @the-going
Signed-off-by: Igor Pecovnik <igor.pecovnik@gmail.com>