coverity/s390x: avoid false positive in kvm_irqchip_add_adapter_route

Paolo Bonzini reported that Coverity reports an uninitialized pad value.
Let's use a designated initializer for kvm_irq_routing_entry to avoid
this false positive. This is similar to kvm_irqchip_add_msi_route and
other users of kvm_irq_routing_entry.
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

kvm-all.c

@@ -1277,7 +1277,7 @@ static int kvm_irqchip_assign_irqfd(KVMState *s, int fd, int rfd, int virq,
 
 int kvm_irqchip_add_adapter_route(KVMState *s, AdapterInfo *adapter)
 {
-    struct kvm_irq_routing_entry kroute;
+    struct kvm_irq_routing_entry kroute = {};
     int virq;
 
     if (!kvm_gsi_routing_enabled()) {