dm: add error handling support for add_disk()

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I81XCK


CVE: NA

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NULL pointer dereference and uaf will be triggered in del_gendisk() if
add_disk has not complete.
Clear request_queue and gendisk early if add_disk fail.

Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com>