tuned-ppd: Count profile hold cookies from 1

Counting from 0 causes issues for gnome-settings-daemon,
for which a null cookie means that it currently has no
active hold.

tuned/ppd/controller.py

@@ -42,7 +42,7 @@ def as_dict(self):
 class ProfileHoldManager(object):
     def __init__(self, controller):
         self._holds = {}
-        self._cookie_counter = 0
+        self._cookie_counter = 1
         self._controller = controller
 
     def _callback(self, cookie, app_id):