Revert "selinux: When adding userdata labels, do cache too"

This reverts commit afc42b0c00b5e313ca71e1d5ca9c6ed05a0ef116.
Revert "selinux: Use a more reliable sentinel to flag /data labelling"

This reverts commit 26ac8dda78498fe940faa52f2bcc5878391f9da9.
Revert "Add SELinux filesystem init (credit rmcc)"

This reverts commit afa42e15c5c6042bb0e820e681dc6db67cafd1ba.