Use idr_for_each_entry to simplify removing all devices.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Link: https://lore.kernel.org/r/20210623145908.92973-10-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>