[POWERPC] Wrap cpu_die() with CONFIG_HOTPLUG_CPU

Per email discussion, it appears that rtas_stop_self()
and pSeries_mach_cpu_die() should not be compiled if
CONFIG_HOTPLUG_CPU is not defined. This patch adds
#ifdefs around these bits of code.

Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/kernel/rtas.c

@@ -810,9 +810,9 @@ 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 = {
+static struct rtas_args rtas_stop_self_args = {
 	/* The token is initialized for real in setup_system() */
 	.token = RTAS_UNKNOWN_SERVICE,
 	.nargs = 0,
@@ -834,6 +834,7 @@ void rtas_stop_self(void)
 
 	panic("Alas, I survived.\n");
 }
+#endif
 
 /*
  * Call early during boot, before mem init or bootmem, to retrieve the RTAS