pcnet: make subsystem vendor id match hardware

Real pcnet device (AT2450) apparently has subsystem
device and vendor id set to 0, this is out of spec
(which requires that vendor id is obtained from PCI SIG)
but windows xp driver seems to need this in order
to associate.

qemu sets pci subsystem id to qumranet/qemu
since d350d97d,
debian does not yet have this patch.

https://bugzilla.redhat.com/show_bug.cgi?id=521247Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Anthony Liguori <aliguori@us.ibm.com>

hw/pcnet.c

@@ -1997,6 +1997,9 @@ static int pci_pcnet_init(PCIDevice *pci_dev)
     pci_set_long(pci_conf + PCI_BASE_ADDRESS_0 + 4,
                  PCI_BASE_ADDRESS_SPACE_MEMORY);
 
+    pci_set_word(pci_conf + PCI_SUBSYSTEM_VENDOR_ID, 0x0);
+    pci_set_word(pci_conf + PCI_SUBSYSTEM_ID, 0x0);
+
     /* TODO: value must be 0 at RST# */
     pci_conf[PCI_INTERRUPT_PIN] = 1; // interrupt pin 0
     pci_conf[PCI_MIN_GNT] = 0x06;