s390/cputime: fix guest/irq/softirq times after CPU hotplug

On CPU hotplug some cpu stats contain bogus values:

$ cat /proc/stat
cpu 0 0 49 1280 0 0 0 3 0 0
cpu0 0 0 49 618 0 0 0 3 0 0
cpu1 0 0 0 662 0 0 0 0 0 0
[...]
$ echo 0 > /sys/devices/system/cpu/cpu1/online
$ echo 1 > /sys/devices/system/cpu/cpu1/online
$ cat /proc/stat
cpu 0 0 49 3200 0 450359962737 450359962737 3 0 0
cpu0 0 0 49 1956 0 0 0 3 0 0
cpu1 0 0 0 1244 0 450359962737 450359962737 0 0 0
[...]

pcpu_attach_task() needs the same assignments as vtime_task_switch.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Fixes: b7394a5f ("sched/cputime, s390: Implement delayed accounting of system time")
Cc: stable@vger.kernel.org # 4.11+
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kernel/smp.c

@@ -293,7 +293,10 @@ static void pcpu_attach_task(struct pcpu *pcpu, struct task_struct *tsk)
 	lc->lpp = LPP_MAGIC;
 	lc->current_pid = tsk->pid;
 	lc->user_timer = tsk->thread.user_timer;
+	lc->guest_timer = tsk->thread.guest_timer;
 	lc->system_timer = tsk->thread.system_timer;
+	lc->hardirq_timer = tsk->thread.hardirq_timer;
+	lc->softirq_timer = tsk->thread.softirq_timer;
 	lc->steal_timer = 0;
 }