block: add new fields in request_queue

hulk inclusion
category: performance
bugzilla: https://gitee.com/openeuler/kernel/issues/I5QK5M


CVE: NA

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Add a new flag QUEUE_FLAG_DISPATCH_ASYNC and two new fields
'dispatch_cpumask' and 'last_dispatch_cpu' for request_queue, prepare
to support dispatch bio asynchronous in specified cpus. This patch also
add sysfs apis.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>