Fix compute_driver_mapping include in nova-compute queens

Change-Id: I8669ae15efbf24cc245f7ace548710907818dd6f
diff --git a/nova/files/queens/nova-compute.conf.Debian b/nova/files/queens/nova-compute.conf.Debian
index 3d5946c..d471a26 100644
--- a/nova/files/queens/nova-compute.conf.Debian
+++ b/nova/files/queens/nova-compute.conf.Debian
@@ -1,4 +1,4 @@
-{%- from "nova/map.jinja" import compute with context %}
+{%- from "nova/map.jinja" import compute,compute_driver_mapping with context %}
 [DEFAULT]
 
 #