mm/swap: fix the obsolete comment for SWP_TYPE_SHIFT

Since commit 3159f943 ("xarray: Replace exceptional entries"), there
is only one bit of 'type' can be shifted up.  Update the corresponding
comment.

Link: https://lkml.kernel.org/r/20220509131416.17553-13-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>

include/linux/swapops.h

@@ -13,10 +13,10 @@
  * get good packing density in that tree, so the index should be dense in
  * the low-order bits.
  *
- * We arrange the `type' and `offset' fields so that `type' is at the seven
+ * We arrange the `type' and `offset' fields so that `type' is at the six
  * high-order bits of the swp_entry_t and `offset' is right-aligned in the
  * remaining bits.  Although `type' itself needs only five bits, we allow for
- * shmem/tmpfs to shift it all up a further two bits: see swp_to_radix_entry().
+ * shmem/tmpfs to shift it all up a further one bit: see swp_to_radix_entry().
  *
  * swp_entry_t's are *never* stored anywhere in their arch-dependent format.
  */