Revert "blk-cgroup: simplify blkg freeing from initialization failure paths"

It turns out this was too soon.  blkg_conf_prep does to funky locking games
with the queue lock for this to work properly.

This reverts commit 27b642b0.

Reported-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230209053523.437927-1-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>