blk-mq: Add blk_mq_alloc_map_and_rqs()

mainline inclusion
from mainline-v5.16-rc1
commit 63064be1
category: performance
bugzilla: 186917, https://gitee.com/openeuler/kernel/issues/I5N1S5
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=63064be150e4b1ba1e4af594ef5aa81adf21a52d



--------------------------------

Add a function to combine allocating tags and the associated requests,
and factor out common patterns to use this new function.

Some function only call blk_mq_alloc_map_and_rqs() now, but more
functionality will be added later.

Also make blk_mq_alloc_rq_map() and blk_mq_alloc_rqs() static since they
are only used in blk-mq.c, and finally rename some functions for
conciseness and consistency with other function names:
- __blk_mq_alloc_map_and_{request -> rqs}()
- blk_mq_alloc_{map_and_requests -> set_map_and_rqs}()

Suggested-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/1633429419-228500-11-git-send-email-john.garry@huawei.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>