Defer TLS key handler registration

Wait until the object is logged in before trying to set
the key handler.  It carries some prerequisite on talking
to the BMC, so it is better handled in the logged handler.

confluent_server/confluent/plugins/hardwaremanagement/ipmi.py

@@ -346,7 +346,6 @@ class IpmiHandler(object):
                     raise exc.TargetEndpointUnreachable(ge[1])
                 raise
         self.ipmicmd = persistent_ipmicmds[(node, tenant)]
-        self.ipmicmd.setup_confluent_keyhandler()
 
     bootdevices = {
         'optical': 'cd'
@@ -358,6 +357,7 @@ class IpmiHandler(object):
             self.error = response['error']
         else:
             self.loggedin = True
+            self.ipmicmd.setup_confluent_keyhandler()
         self._logevt.set()
 
     def handle_request(self):