PM / Hibernate: Correct additional pages number calculation

The struct bm_block is allocated by chain_alloc(),
so it'd better counting it in LINKED_PAGE_DATA_SIZE.
Signed-off-by: Namhyung Kim <namhyung.kim@lge.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

kernel/power/snapshot.c

@@ -812,7 +812,8 @@ unsigned int snapshot_additional_pages(struct zone *zone)
 	unsigned int res;
 
 	res = DIV_ROUND_UP(zone->spanned_pages, BM_BITS_PER_BLOCK);
-	res += DIV_ROUND_UP(res * sizeof(struct bm_block), PAGE_SIZE);
+	res += DIV_ROUND_UP(res * sizeof(struct bm_block),
+			    LINKED_PAGE_DATA_SIZE);
 	return 2 * res;
 }