This reverts commit cea27eb2a202 ("mm/memory-hotplug: fix lowmem count
overflow when offline pages").
The fixed bug by commit cea27eb was fixed to another way by commit 3dcc0571cd64 ("mm: correctly update zone->managed_pages"). That commit
enhances memory_hotplug.c to adjust totalhigh_pages when hot-removing
memory, for details please refer to: