mm/dirty: replace READ_ONCE() with pudp_get()

mm/dirty: replace READ_ONCE() with pudp_get()

Replace READ_ONCE() with a standard page table accessor i.e pudp_get() that
anyways defaults into READ_ONCE() in cases where platform does not override

Link: https://lkml.kernel.org/r/20251006055214.1845342-1-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Lance Yang <lance.yang@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>