sparc64: fix sparse warning in process_64.c

Fix following warning:
process_64.c:91:25: warning: non-ANSI function declaration of function 'arch_cpu_idle_dead'

Add proper (void) to function definition
Signed-off-by: NSam Ravnborg <sam@ravnborg.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

arch/sparc/kernel/process_64.c

@@ -88,7 +88,7 @@ void arch_cpu_idle(void)
 }
 
 #ifdef CONFIG_HOTPLUG_CPU
-void arch_cpu_idle_dead()
+void arch_cpu_idle_dead(void)
 {
 	sched_preempt_enable_no_resched();
 	cpu_play_dead();