powerpc/mm: Use memblock API for PPC32 page_is_ram

To support accurate checking for different blocks of memory on PPC32,
use the same memblock-based approach that's already used on PPC64 also
on PPC32.
Signed-off-by: NJonathan Neuschäfer <j.neuschaefer@gmx.net>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

arch/powerpc/mm/mem.c

@@ -82,11 +82,7 @@ static inline pte_t *virt_to_kpte(unsigned long vaddr)
 
 int page_is_ram(unsigned long pfn)
 {
-#ifndef CONFIG_PPC64	/* XXX for now */
-	return pfn < max_pfn;
-#else
 	return memblock_is_memory(__pfn_to_phys(pfn));
-#endif
 }
 
 pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,