powerpc: Fix compiler warning in arch/powerpc/mm/mem.c

Explicitly cast to unsigned long long, rather than u64.
Signed-off-by: Tony Breeds <tony@bakeyournoodle.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/mm/mem.c

@@ -311,7 +311,7 @@ void __init paging_init(void)
 #endif /* CONFIG_HIGHMEM */
 
 	printk(KERN_DEBUG "Top of RAM: 0x%llx, Total RAM: 0x%lx\n",
-	       (u64)top_of_ram, total_ram);
+	       (unsigned long long)top_of_ram, total_ram);
 	printk(KERN_DEBUG "Memory hole size: %ldMB\n",
 	       (long int)((top_of_ram - total_ram) >> 20));
 	memset(max_zone_pfns, 0, sizeof(max_zone_pfns));