xen/pt: Don't slurp wholesale the PCI configuration registers

Instead we have the emulation registers ->init functions which
consult the host values to see what the initial value should be
and they are responsible for populating the dev.config.
Reviewed-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>

hw/xen/xen_pt.c

@@ -790,12 +790,7 @@ static int xen_pt_initfn(PCIDevice *d)
     }
 
     /* Initialize virtualized PCI configuration (Extended 256 Bytes) */
-    rc = xen_host_pci_get_block(&s->real_device, 0, d->config,
-                                PCI_CONFIG_SPACE_SIZE);
-    if (rc < 0) {
-        XEN_PT_ERR(d,"Could not read PCI_CONFIG space! (rc:%d)\n", rc);
-        goto err_out;
-    }
+    memset(d->config, 0, PCI_CONFIG_SPACE_SIZE);
 
     s->memory_listener = xen_pt_memory_listener;
     s->io_listener = xen_pt_io_listener;