ACPI: HMAT: use hotplug_memory_notifier() directly

Commit 76ae8474 ("Documentation: raise minimum supported version of
GCC to 5.1") updated the minimum gcc version to 5.1.  So the problem
mentioned in f02c6968 ("include/linux/memory.h: implement
register_hotmemory_notifier()") no longer exist.  So we can now switch to
use hotplug_memory_notifier() directly rather than
register_hotmemory_notifier().

Link: https://lkml.kernel.org/r/20220923033347.3935160-7-liushixin2@huawei.comSigned-off-by: Liu Shixin <liushixin2@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Waiman Long <longman@redhat.com>
Cc: zefan li <lizefan.x@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

drivers/acpi/numa/hmat.c

@@ -767,11 +767,6 @@ static int hmat_callback(struct notifier_block *self,
 	return NOTIFY_OK;
 }
 
-static struct notifier_block hmat_callback_nb = {
-	.notifier_call = hmat_callback,
-	.priority = 2,
-};
-
 static __init void hmat_free_structures(void)
 {
 	struct memory_target *target, *tnext;
@@ -854,7 +849,7 @@ static __init int hmat_init(void)
 	hmat_register_targets();
 
 	/* Keep the table and structures if the notifier may use them */
-	if (!register_hotmemory_notifier(&hmat_callback_nb))
+	if (!hotplug_memory_notifier(hmat_callback, 2))
 		return 0;
 out_put:
 	hmat_free_structures();