PPC32: use page_to_pfn instead of page - mem_map in a couple of places

include/asm-ppc/io.h

@@ -295,7 +295,7 @@ extern inline void * phys_to_virt(unsigned long address)
 /*
  * Change "struct page" to physical address.
  */
-#define page_to_phys(page)	((page - mem_map) << PAGE_SHIFT)
+#define page_to_phys(page)	(page_to_pfn(page) << PAGE_SHIFT)
 #define page_to_bus(page)	(page_to_phys(page) + PCI_DRAM_OFFSET)
 
 #endif /* __KERNEL__ */

include/asm-ppc/pgalloc.h

@@ -26,7 +26,7 @@ extern void pgd_free(pgd_t *pgd);
 #define pmd_populate_kernel(mm, pmd, pte)	\
 		(pmd_val(*(pmd)) = __pa(pte))
 #define pmd_populate(mm, pmd, pte)	\
-		(pmd_val(*(pmd)) = ((pte) - mem_map) << PAGE_SHIFT)
+		(pmd_val(*(pmd)) = (page_to_pfn(pte) << PAGE_SHIFT))
 
 extern pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long addr);
 extern struct page *pte_alloc_one(struct mm_struct *mm, unsigned long addr);