mm,memory_hotplug: drop status_change_nid parameter from memory_notify

There no users left of status_change_nid, so drop it from memory_notify
struct.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Oscar Salvador <[e-mail]>
Suggested-by: David Hildenbrand <[e-mail]>
Acked-by: David Hildenbrand <[e-mail]>
Reviewed-by: Vlastimil Babka <[e-mail]>
Cc: Harry Yoo <[e-mail]>
Cc: Hyeonggon Yoo <[e-mail]>
Cc: Joanthan Cameron <[e-mail]>
Cc: Rakie Kim <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

Documentation/core-api/memory-hotplug.rst

···
 	struct memory_notify {
 		unsigned long start_pfn;
 		unsigned long nr_pages;
-		int status_change_nid;
 	}
 
 - start_pfn is start_pfn of online/offline memory.
 - nr_pages is # of pages of online/offline memory.
-- status_change_nid is set node id when N_MEMORY of nodemask is (will be)
-  set/clear. It means a new(memoryless) node gets new memory by online and a
-  node loses all memory. If this is -1, then nodemask status is not changed.
-
-  If status_changed_nid* >= 0, callback should create/discard structures for the
-  node if necessary.
 
 It is possible to get notified for MEM_CANCEL_ONLINE without having been notified
 for MEM_GOING_ONLINE, and the same applies to MEM_CANCEL_OFFLINE and

include/linux/memory.h

···
 	unsigned long altmap_nr_pages;
 	unsigned long start_pfn;
 	unsigned long nr_pages;
-	int status_change_nid;
 };
 
 struct notifier_block;

mm/memory_hotplug.c

···
 	struct memory_notify mem_arg = {
 		.start_pfn = pfn,
 		.nr_pages = nr_pages,
-		.status_change_nid = NUMA_NO_NODE,
 	};
 	struct node_notify node_arg = {
 		.nid = NUMA_NO_NODE,
···
 	if (!node_state(nid, N_MEMORY)) {
 		/* Adding memory to the node for the first time */
 		node_arg.nid = nid;
-		mem_arg.status_change_nid = nid;
 		ret = node_notify(NODE_ADDING_FIRST_MEMORY, &node_arg);
 		ret = notifier_to_errno(ret);
 		if (ret)
···
 	struct memory_notify mem_arg = {
 		.start_pfn = start_pfn,
 		.nr_pages = nr_pages,
-		.status_change_nid = NUMA_NO_NODE,
 	};
 	struct node_notify node_arg = {
 		.nid = NUMA_NO_NODE,
···
 	 */
 	if (nr_pages >= pgdat->node_present_pages) {
 		node_arg.nid = node;
-		mem_arg.status_change_nid = node;
 		ret = node_notify(NODE_REMOVING_LAST_MEMORY, &node_arg);
 		ret = notifier_to_errno(ret);
 		if (ret) {