KVM: Return -ENOTTY on unrecognized ioctls

Not the incorrect -EINVAL.

Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 07ced89..00e2ce8 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -150,7 +150,7 @@
 		break;
 	}
 	default:
-		r = -EINVAL;
+		r = -ENOTTY;
 	}
 
 	return r;