ppc64: make G5 setup compile again

The stop_self thing is accessed unconditionally from pSeries_setup.c

arch/ppc64/kernel/rtas.c

@@ -516,7 +516,6 @@ asmlinkage int ppc_rtas(struct rtas_args __user *uargs)
 	return 0;
 }
 
-#ifdef CONFIG_HOTPLUG_CPU
 /* This version can't take the spinlock, because it never returns */
 
 struct rtas_args rtas_stop_self_args = {
@@ -541,7 +540,6 @@ void rtas_stop_self(void)
 
 	panic("Alas, I survived.\n");
 }
-#endif /* CONFIG_HOTPLUG_CPU */
 
 /*
  * Return the firmware-specified size of the error log buffer