mm: remove obsolete comment in do_fault_around()

Since commit 7267ec00 ("mm: postpone page table allocation until we
have page to map"), do_fault_around is not called with page table lock
held.  Cleanup the corresponding comments.

Link: https://lkml.kernel.org/r/20220716080359.38791-1-linmiaohe@huawei.comSigned-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/memory.c

@@ -4439,10 +4439,6 @@ late_initcall(fault_around_debugfs);
  * It uses vm_ops->map_pages() to map the pages, which skips the page if it's
  * not ready to be mapped: not up-to-date, locked, etc.
  *
- * This function is called with the page table lock taken. In the split ptlock
- * case the page table lock only protects only those entries which belong to
- * the page table corresponding to the fault address.
- *
  * This function doesn't cross the VMA boundaries, in order to call map_pages()
  * only once.
  *