mm/ptdump: replace READ_ONCE() with standard page table accessors

mm/ptdump: replace READ_ONCE() with standard page table accessors

Replace READ_ONCE() with standard page table accessors i.e pxdp_get()
which anyways default into READ_ONCE() in cases where platform does not
override.  Also convert ptep_get_lockless() into ptep_get() as well.

Link: https://lkml.kernel.org/r/20251001042502.1400726-1-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Acked-by: Lance Yang <lance.yang@linux.dev>
Acked-by: SeongJae Park <sj@kernel.org>
Acked-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>