savevm: Add DeviceState param

When available, we'd like to be able to access the DeviceState
when registering a savevm.  For buses with a get_dev_path()
function, this will allow us to create more unique savevm
id strings.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/slirp/slirp.c b/slirp/slirp.c
index 3c785cd..82fd9b4 100644
--- a/slirp/slirp.c
+++ b/slirp/slirp.c
@@ -232,7 +232,8 @@
 
     slirp->opaque = opaque;
 
-    register_savevm("slirp", 0, 3, slirp_state_save, slirp_state_load, slirp);
+    register_savevm(NULL, "slirp", 0, 3,
+                    slirp_state_save, slirp_state_load, slirp);
 
     QTAILQ_INSERT_TAIL(&slirp_instances, slirp, entry);
 
@@ -243,7 +244,7 @@
 {
     QTAILQ_REMOVE(&slirp_instances, slirp, entry);
 
-    unregister_savevm("slirp", slirp);
+    unregister_savevm(NULL, "slirp", slirp);
 
     qemu_free(slirp->tftp_prefix);
     qemu_free(slirp->bootp_filename);