Revert "rootdir: init.rc: Fix for "add_tid_to_cgroup failed to write" warnings"

Ummm, this is a directory, not a file.  This commit just removed the ability to
access this directory for anything except a root process running with dac_override
and/or dac_read_search capabilities.

drw-rw---- 3 system system 0 1970-12-12 12:17 /dev/cpuctl

This reverts commit 4fdff17b.

Change-Id: I3b30b7e2f5d67c987f53e80f5fbe0570e30e0f64