vfio/pci: Default display option to "off"

Commit a9994687 ("vfio/display: core & wireup") added display
support to vfio-pci with the default being "auto", which breaks
existing VMs when the vGPU requires GL support but had no previous
requirement for a GL compatible configuration.  "Off" is the safer
default as we impose no new requirements to VM configurations.

Fixes: a9994687 ("vfio/display: core & wireup")
Cc: qemu-stable@nongnu.org
Cc: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: NAlex Williamson <alex.williamson@redhat.com>

hw/vfio/pci.c

@@ -3160,7 +3160,7 @@ static Property vfio_pci_dev_properties[] = {
     DEFINE_PROP_PCI_HOST_DEVADDR("host", VFIOPCIDevice, host),
     DEFINE_PROP_STRING("sysfsdev", VFIOPCIDevice, vbasedev.sysfsdev),
     DEFINE_PROP_ON_OFF_AUTO("display", VFIOPCIDevice,
-                            display, ON_OFF_AUTO_AUTO),
+                            display, ON_OFF_AUTO_OFF),
     DEFINE_PROP_UINT32("x-intx-mmap-timeout-ms", VFIOPCIDevice,
                        intx.mmap_timeout, 1100),
     DEFINE_PROP_BIT("x-vga", VFIOPCIDevice, features,