block: don't delete queue kobject before its children

In the Linux kernel, the following vulnerability has been resolved:

block: don't delete queue kobject before its children

kobjects aren't supposed to be deleted before their child kobjects are

deleted. Apparently this is usually benign; however, a WARN will be

triggered if one of the child kobjects has a named attribute group:

sysfs group 'modes' not found for kobject 'crypto'

WARNING: CPU: 0 PID: 1 at fs/sysfs/group.c:278 sysfs_remove_group+0x72/0x80

...

Call Trace:

sysfs_remove_groups+0x29/0x40 fs/sysfs/group.c:312

__kobject_del+0x20/0x80 lib/kobject.c:611

kobject_cleanup+0xa4/0x140 lib/kobject.c:696

kobject_release lib/kobject.c:736 [inline]

kref_put include/linux/kref.h:65 [inline]

kobject_put+0x53/0x70 lib/kobject.c:753

blk_crypto_sysfs_unregister+0x10/0x20 block/blk-crypto-sysfs.c:159

blk_unregister_queue+0xb0/0x110 block/blk-sysfs.c:962

del_gendisk+0x117/0x250 block/genhd.c:610

Fix this by moving the kobject_del() and the corresponding

kobject_uevent() to the correct place.