[VTPM] Make vTPM hotplug scripts use the UUID of the vTPM instance

Make the vTPM hotplug script use the UUID of the vTPM instance for
associating it with its instance number rather than the name of the
domain.
Also change the cleanup in the xm test to use the atexit mechanism
rather than explicitly calling a function to clean up.

Signed-off-by: Stefan Berger <stefanb@us.ibm.com>

tools/python/xen/xend/XendDevices.py

@@ -78,6 +78,7 @@ class XendDevices:
         @param domain: domain this controller is handling devices for.
         @type domain: XendDomainInfo
         """
-        tpmif.destroy_vtpmstate(domain.getName())
+        from xen.xend.XendLogging import log
+        tpmif.destroy_vtpmstate(domain.info.get('vtpm_refs'))
 
     destroy_device_state = classmethod(destroy_device_state)

tools/python/xen/xend/server/tpmif.py

@@ -31,9 +31,10 @@ import re
 
 xoptions = XendOptions.instance()
 
-def destroy_vtpmstate(name):
+def destroy_vtpmstate(uuids):
     if os.path.exists(VTPM_DELETE_SCRIPT):
-        os.system(VTPM_DELETE_SCRIPT + " " + name)
+        for uuid in uuids:
+            os.system(VTPM_DELETE_SCRIPT + " " + uuid)
 
 class TPMifController(DevController):
     """TPM interface controller. Handles all TPM devices for a domain.