mm/vmalloc.c: make use of the helper macro LIST_HEAD()

list_head can be initialized automatically with LIST_HEAD() instead of
calling INIT_LIST_HEAD().  Here we can simplify the code.

Link: https://lkml.kernel.org/r/20240828041216.1222582-1-lihongbo22@huawei.comSigned-off-by: Hongbo Li <lihongbo22@huawei.com>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/vmalloc.c

@@ -2131,23 +2131,18 @@ reclaim_list_global(struct list_head *head)
 static void
 decay_va_pool_node(struct vmap_node *vn, bool full_decay)
 {
+	LIST_HEAD(decay_list);
+	struct rb_root decay_root = RB_ROOT;
 	struct vmap_area *va, *nva;
-	struct list_head decay_list;
-	struct rb_root decay_root;
 	unsigned long n_decay;
 	int i;
 
-	decay_root = RB_ROOT;
-	INIT_LIST_HEAD(&decay_list);
-
 	for (i = 0; i < MAX_VA_SIZE_PAGES; i++) {
-		struct list_head tmp_list;
+		LIST_HEAD(tmp_list);
 
 		if (list_empty(&vn->pool[i].head))
 			continue;
 
-		INIT_LIST_HEAD(&tmp_list);
-
 		/* Detach the pool, so no-one can access it. */
 		spin_lock(&vn->pool_lock);
 		list_replace_init(&vn->pool[i].head, &tmp_list);