aoe: clean device rq_list in aoedev_downdev()

aoe: clean device rq_list in aoedev_downdev()

An aoe device's rq_list contains accepted block requests that are
waiting to be transmitted to the aoe target. This queue was added as
part of the conversion to blk_mq. However, the queue was not cleaned out
when an aoe device is downed which caused blk_mq_freeze_queue() to sleep
indefinitely waiting for those requests to complete, causing a hang. This
fix cleans out the queue before calling blk_mq_freeze_queue().

Link: https://bugzilla.kernel.org/show_bug.cgi?id=212665
Fixes: 3582dd291788 ("aoe: convert aoeblk to blk-mq")
Signed-off-by: Justin Sanders <jsanders.devel@gmail.com>
Link: https://lore.kernel.org/r/20250610170600.869-1-jsanders.devel@gmail.com
Tested-By: Valentin Kleibel <valentin@vrvis.at>
Signed-off-by: Jens Axboe <axboe@kernel.dk>