virtio: Use pci_enable_msix_exact() instead of pci_enable_msix()

As result of deprecation of MSI-X/MSI enablement functions
pci_enable_msix() and pci_enable_msi_block() all drivers
using these two interfaces need to be updated to use the
new pci_enable_msi_range()  or pci_enable_msi_exact()
and pci_enable_msix_range() or pci_enable_msix_exact()
interfaces.
Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

drivers/virtio/virtio_pci.c

@@ -333,10 +333,8 @@ static int vp_request_msix_vectors(struct virtio_device *vdev, int nvectors,
 	for (i = 0; i < nvectors; ++i)
 		vp_dev->msix_entries[i].entry = i;
 
-	/* pci_enable_msix returns positive if we can't get this many. */
-	err = pci_enable_msix(vp_dev->pci_dev, vp_dev->msix_entries, nvectors);
-	if (err > 0)
-		err = -ENOSPC;
+	err = pci_enable_msix_exact(vp_dev->pci_dev,
+				    vp_dev->msix_entries, nvectors);
 	if (err)
 		goto error;
 	vp_dev->msix_enabled = 1;