block, bfq: use helper macro RQ_BFQQ to get bfqq of request

Use helper macro RQ_BFQQ to get bfqq of request.

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230116095153.3810101-5-shikemeng@huaweicloud.com


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