xen: only check xen_platform_pci_unplug if hvm

commit b9136d207f08
  xen: initialize platform-pci even if xen_emul_unplug=never

breaks blkfront/netfront by not loading them because of
xen_platform_pci_unplug=0 and it is never set for PV guest.

Signed-off-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

drivers/block/xen-blkfront.c

@@ -1452,7 +1452,7 @@ static int __init xlblk_init(void)
 	if (!xen_domain())
 		return -ENODEV;
 
-	if (!xen_platform_pci_unplug)
+	if (xen_hvm_domain() && !xen_platform_pci_unplug)
 		return -ENODEV;
 
 	if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {

drivers/net/xen-netfront.c

@@ -1957,7 +1957,7 @@ static int __init netif_init(void)
 	if (xen_initial_domain())
 		return 0;
 
-	if (!xen_platform_pci_unplug)
+	if (xen_hvm_domain() && !xen_platform_pci_unplug)
 		return -ENODEV;
 
 	printk(KERN_INFO "Initialising Xen virtual ethernet driver.\n");