mm/hugetlb: convert use of struct page to folio in __unmap_hugepage_range()

In __unmap_hugepage_range(), the "page" pointer always points to the first
page of a huge page, which guarantees there is a folio associating with
it.  Convert the "page" pointer to use folio.

Link: https://lkml.kernel.org/r/20250505182345.506888-6-nifan.cxl@gmail.com


Signed-off-by: Fan Ni <fan.ni@samsung.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: "Vishal Moola (Oracle)" <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>