qemu: make cirrus init value pci spec compliant

PCI memory should be disabled at reset, otherwise
we might claim transactions at address 0.
I/O should also be disabled, although for cirrus
it is harmless to enable it as we do not
have I/O bar.

Note: bios fix needed for this patch to work
was already applied:
previously bios incorrently assumed that it does not
need to enable i/o unless device has i/o bar.
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Acked-by: NJuan Quintela <quintela@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

hw/cirrus_vga.c

@@ -3231,7 +3231,6 @@ static int pci_cirrus_vga_initfn(PCIDevice *dev)
      /* setup PCI */
      pci_config_set_vendor_id(pci_conf, PCI_VENDOR_ID_CIRRUS);
      pci_config_set_device_id(pci_conf, device_id);
-     pci_conf[0x04] = PCI_COMMAND_IOACCESS | PCI_COMMAND_MEMACCESS;
      pci_config_set_class(pci_conf, PCI_CLASS_DISPLAY_VGA);
      pci_conf[PCI_HEADER_TYPE] = PCI_HEADER_TYPE_NORMAL;