fs: Fix not being able to read last sector of memdisk
fs: Fix not being able to read last sector of memdisk

hioa-cs/IncludeOS,alfred-bratterud/IncludeOS,mnordsletten/IncludeOS,AnnikaH/IncludeOS,ingve/IncludeOS,AndreasAakesson/IncludeOS,alfred-bratterud/IncludeOS,hioa-cs/IncludeOS,ingve/IncludeOS,mnordsletten/IncludeOS,AndreasAakesson/IncludeOS,mnordsletten/IncludeOS,mnordsletten/IncludeOS,hioa-cs/IncludeOS,ingve/IncludeOS,ingve/IncludeOS,alfred-bratterud/IncludeOS,hioa-cs/IncludeOS,mnordsletten/IncludeOS,mnordsletten/IncludeOS,AndreasAakesson/IncludeOS,AndreasAakesson/IncludeOS,AnnikaH/IncludeOS,alfred-bratterud/IncludeOS,hioa-cs/IncludeOS,ingve/IncludeOS,AndreasAakesson/IncludeOS,AnnikaH/IncludeOS,AnnikaH/IncludeOS,AndreasAakesson/IncludeOS,AnnikaH/IncludeOS,alfred-bratterud/IncludeOS