Revert "blk-mq, elevator: Count requests per hctx to improve performance"

mainline inclusion
from mainline-5.12-rc1
commit 5ac83c64
category: perf
bugzilla: https://gitee.com/openeuler/kernel/issues/I4SW26
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5ac83c644f5fb924f0b2c09102ab82fc788f8411



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This reverts commit b445547e.

Since both mq-deadline and BFQ completely ignore hctx they are passed to
their dispatch function and dispatch whatever request they deem fit
checking whether any request for a particular hctx is queued is just
pointless since we'll very likely get a request from a different hctx
anyway. In the following commit we'll deal with lock contention in these
IO schedulers in presence of multiple HW queues in a different way.

Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Conflicts:
	block/bfq-iosched.c

Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>