mm/demotion: fix kernel error with memory hotplug

mm/demotion: fix kernel error with memory hotplug

On memory hot unplug, the kernel removes the node memory type from the
associated memory tier.  Use list_del_init instead of list del such that
the same memory type can be added back to a memory tier on hotplug.

Without this, we get the below warning and return error on
adding memory type to a new memory tier.

[   33.596095] ------------[ cut here ]------------
[   33.596099] WARNING: CPU: 3 PID: 667 at mm/memory-tiers.c:115 set_node_memory_tier+0xd6/0x2e0
[   33.596109] Modules linked in: kmem

...

[   33.596126] RIP: 0010:set_node_memory_tier+0xd6/0x2e0

....
[   33.596196]  memtier_hotplug_callback+0x48/0x68
[   33.596204]  blocking_notifier_call_chain+0x80/0xc0
[   33.596211]  online_pages+0x25e/0x280
[   33.596218]  memory_block_change_state+0x176/0x1f0
[   33.596225]  memory_subsys_online+0x37/0x40
[   33.596230]  online_store+0x9b/0x130
[   33.596236]  kernfs_fop_write_iter+0x128/0x1b0
[   33.596242]  vfs_write+0x24b/0x2c0
[   33.596249]  ksys_write+0x74/0xe0
[   33.596254]  do_syscall_64+0x43/0x90
[   33.596259]  entry_SYSCALL_64_after_hwframe+0x63/0xcd

Link: https://lkml.kernel.org/r/20220825092019.379069-1-aneesh.kumar@linux.ibm.com
Fixes: "mm/demotion: Add hotplug callbacks to handle new numa node onlined"
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Bharata B Rao <bharata@amd.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Hesham Almatary <hesham.almatary@huawei.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Jagdish Gediya <jvgediya.oss@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Tim Chen <tim.c.chen@intel.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>