pci: remove PCIDeviceInfo::header_type

replace PCIDeviceInfo::header_type with is_bridge
as suggested by Michael S. Tsirkin <mst@redhat.com>

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
diff --git a/hw/apb_pci.c b/hw/apb_pci.c
index 6dd529f..69a774d 100644
--- a/hw/apb_pci.c
+++ b/hw/apb_pci.c
@@ -434,7 +434,7 @@
     .qdev.name = "pbm",
     .qdev.size = sizeof(PCIDevice),
     .init      = pbm_pci_host_init,
-    .header_type  = PCI_HEADER_TYPE_BRIDGE,
+    .is_bridge = 1,
 };
 
 static SysBusDeviceInfo pbm_host_info = {