block: add blk_alloc_disk and blk_cleanup_disk APIs

mainline inclusion
from mainline-v5.14-rc1
commit f525464a
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I81XCK

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=f525464a8000f092c20b00eead3eaa9d849c599e



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Add two new APIs to allocate and free a gendisk including the
request_queue for use with BIO based drivers.  This is to avoid
boilerplate code in drivers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20210521055116.1053587-6-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>
conflicts:
 block/genhd.c
 include/linux/genhd.h
Signed-off-by: Zhong Jinghua <zhongjinghua@huawei.com>
Signed-off-by: Li Nan <linan122@huawei.com>
(cherry picked from commit b4365f09)