mm/swap: clean up the comment of find_next_to_unuse

Since commit 10a9c496 ("mm: simplify try_to_unuse"), frontswap
parameter is removed.  Update the corresponding comment.

Link: https://lkml.kernel.org/r/20220509131416.17553-14-linmiaohe@huawei.comSigned-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: NeilBrown <neilb@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/swapfile.c

@@ -1990,9 +1990,9 @@ static int unuse_mm(struct mm_struct *mm, unsigned int type)
 }
 
 /*
- * Scan swap_map (or frontswap_map if frontswap parameter is true)
- * from current position to next entry still in use. Return 0
- * if there are no inuse entries after prev till end of the map.
+ * Scan swap_map from current position to next entry still in use.
+ * Return 0 if there are no inuse entries after prev till end of
+ * the map.
  */
 static unsigned int find_next_to_unuse(struct swap_info_struct *si,
 					unsigned int prev)