x86, mce: don't init timer if !mce_available

In mce_cpu_restart, mce_init_timer is called unconditionally.
If !mce_available (e.g. mce is disabled), there are no useful work
for timer.  Stop running it.
Signed-off-by: NHidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

arch/x86/kernel/cpu/mcheck/mce.c

@@ -1617,7 +1617,8 @@ static int mce_resume(struct sys_device *dev)
 static void mce_cpu_restart(void *data)
 {
 	del_timer_sync(&__get_cpu_var(mce_timer));
-	if (mce_available(&current_cpu_data))
+	if (!mce_available(&current_cpu_data))
+		return;
 	mce_init();
 	mce_init_timer();
 }