mm/vmscan: remove obsolete comment in get_scan_count

Since commit 1431d4d11a ("mm: base LRU balancing on an explicit cost
model"), the relative value of each set of LRU lists is based on cost
model instead of rotated/scanned ratio.  Cleanup the relevant comment.

Link: https://lkml.kernel.org/r/20220409030245.61211-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/vmscan.c

@@ -2646,9 +2646,7 @@ enum scan_balance {
 
 /*
  * Determine how aggressively the anon and file LRU lists should be
- * scanned.  The relative value of each set of LRU lists is determined
- * by looking at the fraction of the pages scanned we did rotate back
- * onto the active list instead of evict.
+ * scanned.
  *
  * nr[0] = anon inactive pages to scan; nr[1] = anon active pages to scan
  * nr[2] = file inactive pages to scan; nr[3] = file active pages to scan