Documentation/mm: drop pxx_mkdevmap() descriptions from page table helpers

Documentation/mm: drop pxx_mkdevmap() descriptions from page table helpers

Remove pxx_mkdevmap() descriptions, as these helper functions have already
been dropped (including DEBUG_VM_PGTABLE test) via the commit d438d2734170
("mm: remove devmap related functions and page table bits").

Link: https://lkml.kernel.org/r/20250929120045.1109707-1-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>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Alistair Popple <apopple@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>