migrate: Remove references to Private2

These comments are now stale; rewrite them.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/20241002040111.1023018-7-willy@infradead.org
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>

Author: Matthew Wilcox (Oracle)

mm/migrate.c

@@ -472,7 +472,7 @@ static int folio_expected_refs(struct address_space *mapping,
  * The number of remaining references must be:
  * 1 for anonymous folios without a mapping
  * 2 for folios with a mapping
- * 3 for folios with a mapping and PagePrivate/PagePrivate2 set.
+ * 3 for folios with a mapping and the private flag set.
  */
 static int __folio_migrate_mapping(struct address_space *mapping,
 		struct folio *newfolio, struct folio *folio, int expected_count)
@@ -786,7 +786,7 @@ static int __migrate_folio(struct address_space *mapping, struct folio *dst,
  * @mode: How to migrate the page.
  *
  * Common logic to directly migrate a single LRU folio suitable for
- * folios that do not use PagePrivate/PagePrivate2.
+ * folios that do not have private data.
  *
  * Folios are locked upon entry and exit.
  */