Revert "blk-cgroup: support to track if policy is online"

This reverts commit 3154d64f which is
commit dfd6200a upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: I5d09f94759c130efe2d3490c23a251d4d71e6140
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>