pcie: Fix incorrect write to the ari capability next function field

PCI_ARI_CAP_NFN, a macro for reading next function was used instead of
the intended write.

Signed-off-by: Knut Omang <knut.omang@oracle.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/pci/pcie.c

diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
index a123c01..de0e967 100644
--- a/hw/pci/pcie.c
+++ b/hw/pci/pcie.c
@@ -630,5 +630,5 @@
 {
     pcie_add_capability(dev, PCI_EXT_CAP_ID_ARI, PCI_ARI_VER,
                         offset, PCI_ARI_SIZEOF);
-    pci_set_long(dev->config + offset + PCI_ARI_CAP, PCI_ARI_CAP_NFN(nextfn));
+    pci_set_long(dev->config + offset + PCI_ARI_CAP, (nextfn & 0xff) << 8);
 }