m68k: mm: Convert init_pointer_table() to use ptdescs

Motorola uses init_pointer_table() for page tables, so it should be using
struct ptdesc, not struct page.

This helps us prepare to allocate ptdescs as their own memory
descriptor, and prepares to remove 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/20250611001255.527952-4-vishal.moola@gmail.com
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

Author: VMoola

arch/m68k/mm/motorola.c

@@ -121,10 +121,10 @@ void __init init_pointer_table(void *table, int type)
 {
 	ptable_desc *dp;
 	unsigned long ptable = (unsigned long)table;
-	unsigned long page = ptable & PAGE_MASK;
-	unsigned int mask = 1U << ((ptable - page)/ptable_size(type));
+	unsigned long pt_addr = ptable & PAGE_MASK;
+	unsigned int mask = 1U << ((ptable - pt_addr)/ptable_size(type));
 
-	dp = PD_PTABLE(page);
+	dp = PD_PTABLE(pt_addr);
 	if (!(PD_MARKBITS(dp) & mask)) {
 		PD_MARKBITS(dp) = ptable_mask(type);
 		list_add(dp, &ptable_list[type]);
@@ -133,9 +133,9 @@ void __init init_pointer_table(void *table, int type)
 	PD_MARKBITS(dp) &= ~mask;
 	pr_debug("init_pointer_table: %lx, %x\n", ptable, PD_MARKBITS(dp));
 
-	/* unreserve the page so it's possible to free that page */
-	__ClearPageReserved(PD_PAGE(dp));
-	init_page_count(PD_PAGE(dp));
+	/* unreserve the ptdesc so it's possible to free that ptdesc */
+	__ClearPageReserved(ptdesc_page(PD_PTDESC(dp)));
+	init_page_count(ptdesc_page(PD_PTDESC(dp)));
 
 	return;
 }