msix: Add msix_nr_vectors_allocated

Analogously to msi_nr_vectors_allocated, add a service for MSI-X. Will
be used by the virtio-pci layer.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/hw/msix.c b/hw/msix.c
index 1622e16..59c7a83 100644
--- a/hw/msix.c
+++ b/hw/msix.c
@@ -452,6 +452,11 @@
     msix_free_irq_entries(dev);
 }
 
+unsigned int msix_nr_vectors_allocated(const PCIDevice *dev)
+{
+    return dev->msix_entries_nr;
+}
+
 static int msix_set_notifier_for_vector(PCIDevice *dev, unsigned int vector)
 {
     MSIMessage msg;