mm/hugetlb: convert hugetlb_change_protection() to folios

mm/hugetlb: convert hugetlb_change_protection() to folios

The for loop inside hugetlb_change_protection() increments by the huge
page size:

psize = huge_page_size(h);
for (; address < end; address += psize)

so we are operating on the head page of the huge pages between address and
end.  We can safely convert the struct page usage to struct folio.

Link: https://lkml.kernel.org/r/20250528192013.91130-1-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>