s390: fix cpu hotplug / cpu activity on interrupts

The add_del/running_cpu code and env->halted are tracking stopped cpus. Sleeping cpus (idle and enabled for interrupts) are waiting inside the kernel.
No interrupt besides the restart can move a cpu from stopped to operational. This is already handled over there. So lets just remove the bogus wakup from the common interrupt delivery, otherwise any interrupt will wake up a cpu, even if this cpu is stopped (Thus leading to strange hangs on sigp restart)

This fixes
echo 0 > /sys/devices/system/cpu/cpu0/online
echo 1 > /sys/devices/system/cpu/cpu0/online
in the guest

@@ -185,9 +185,6 @@ void kvm_s390_interrupt_internal(CPUState *env, int type, uint32_t parm,
         return;
     }
 
-    s390_add_running_cpu(env);
-    qemu_cpu_kick(env);
-
     kvmint.type = type;
     kvmint.parm = parm;
     kvmint.parm64 = parm64;

Thanks, applied to s390-next

Alex