qemu/virtio: virtio save/load bindings

Implement bindings for virtio save/load. Use them in virtio pci.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/hw/virtio.h b/hw/virtio.h
index e1b31d0..aa55677 100644
--- a/hw/virtio.h
+++ b/hw/virtio.h
@@ -76,6 +76,10 @@
 
 typedef struct {
     void (*notify)(void * opaque, uint16_t vector);
+    void (*save_config)(void * opaque, QEMUFile *f);
+    void (*save_queue)(void * opaque, int n, QEMUFile *f);
+    int (*load_config)(void * opaque, QEMUFile *f);
+    int (*load_queue)(void * opaque, int n, QEMUFile *f);
 } VirtIOBindings;
 
 #define VIRTIO_PCI_QUEUE_MAX 16