mm/writeback: update filemap_dirty_folio() comment

Change to use new address space operation dirty_folio().

Link: https://lkml.kernel.org/r/20230917-trycontrib1-v1-1-db22630b8839@gmail.com
Fixes: 6f31a5a2 ("fs: Add aops->dirty_folio")
Signed-off-by: Jianguo Bau <roidinev@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page-writeback.c

@@ -2679,7 +2679,7 @@ void __folio_mark_dirty(struct folio *folio, struct address_space *mapping,
  * @folio: Folio to be marked as dirty.
  *
  * Filesystems which do not use buffer heads should call this function
- * from their set_page_dirty address space operation.  It ignores the
+ * from their dirty_folio address space operation.  It ignores the
  * contents of folio_get_private(), so if the filesystem marks individual
  * blocks as dirty, the filesystem should handle that itself.
  *