m68k: mm: Convert pointer table macros to use ptdescs

Motorola uses its pointer tables for page tables, so its macros should be
using struct ptdesc, not struct page. This removes a user of page->lru.

Signed-off-by: "Vishal Moola (Oracle)" <vishal.moola@gmail.com>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/20250611001255.527952-5-vishal.moola@gmail.com


Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>