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/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 */
 	}