target/s390x: simplify ri_allowed()

Only used in KVM and there is no reason why it shouldn't be allowed for
tcg - it is simply not available.

Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20170818114353.13455-4-david@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>

hw/s390x/s390-virtio-ccw.c

@@ -278,9 +278,6 @@ static S390CcwMachineClass *get_machine_class(void)
 
 bool ri_allowed(void)
 {
-    if (!kvm_enabled()) {
-        return false;
-    }
     /* for "none" machine this results in true */
     return get_machine_class()->ri_allowed;
 }