cpu hotplug: s390 doesn't support additional_cpus anymore.

s390 doesn't support the additional_cpus kernel parameter anymore since a
long time.  So we better update the code and documentation to reflect
that.

Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/cpu.c b/kernel/cpu.c
index c977c33..f17e985 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -369,7 +369,7 @@
 	if (!cpu_isset(cpu, cpu_possible_map)) {
 		printk(KERN_ERR "can't online cpu %d because it is not "
 			"configured as may-hotadd at boot time\n", cpu);
-#if defined(CONFIG_IA64) || defined(CONFIG_X86_64) || defined(CONFIG_S390)
+#if defined(CONFIG_IA64) || defined(CONFIG_X86_64)
 		printk(KERN_ERR "please check additional_cpus= boot "
 				"parameter\n");
 #endif