virtio_pci: fix level interrupts with irqfd

commit 62c96360ae
    virtio-pci: fix level interrupts
only helps systems without irqfd: on systems with irqfd support we
passed in flag requesting irqfd even when msix is disabled.

As a result, for level interrupts we didn't install an fd handler so
unmasking an fd had no effect.

Fix this up.

Cc: qemu-stable@nongnu.org
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
(cherry picked from commit 23fe2b3f9e)

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

hw/virtio/virtio-pci.c

@@ -799,8 +799,7 @@ static int virtio_pci_set_guest_notifiers(DeviceState *d, int nvqs, bool assign)
             break;
         }
 
-        r = virtio_pci_set_guest_notifier(d, n, assign,
-                                          kvm_msi_via_irqfd_enabled());
+        r = virtio_pci_set_guest_notifier(d, n, assign, with_irqfd);
         if (r < 0) {
             goto assign_error;
         }