btrfs: also use kthread_associate_blkcg for uncompressible ranges
submit_one_async_extent needs to use submit_one_async_extent no matter
if the range it handles ends up beeing compressed or not as the deadlock
risk due to cgroup thottling is the same. Call kthread_associate_blkcg
earlier to cover submit_uncompressed_range case as well.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>