powerpc: Fix memory limits when starting at a non-zero address

memblock_enforce_memory_limit() takes the desired maximum quantity of memory
to end up with, not an address above which memory will not be used.
Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/kernel/prom.c

@@ -97,7 +97,7 @@ static void __init move_device_tree(void)
 	start = __pa(initial_boot_params);
 	size = be32_to_cpu(initial_boot_params->totalsize);
 
-	if ((memory_limit && (start + size) > memory_limit) ||
+	if ((memory_limit && (start + size) > PHYSICAL_START + memory_limit) ||
 			overlaps_crashkernel(start, size)) {
 		p = __va(memblock_alloc(size, PAGE_SIZE));
 		memcpy(p, initial_boot_params, size);

arch/powerpc/mm/init_32.c

@@ -148,7 +148,7 @@ void __init MMU_init(void)
 		lowmem_end_addr = memstart_addr + total_lowmem;
 #ifndef CONFIG_HIGHMEM
 		total_memory = total_lowmem;
-		memblock_enforce_memory_limit(lowmem_end_addr);
+		memblock_enforce_memory_limit(total_lowmem);
 		memblock_analyze();
 #endif /* CONFIG_HIGHMEM */
 	}