Only write out uwsgi configs when deploying API services

Previously this would always happen for Nova and Cinder even if n-api
and c-api were not enabled on the host respectively.

This change stops this by placing both calls write_uwsgi_config behind
is_service_enabled checks.

Change-Id: I997685da771736dbad79bcfe4b00dbc63bd6d6b6
diff --git a/lib/cinder b/lib/cinder
index cefb609..76314c1 100644
--- a/lib/cinder
+++ b/lib/cinder
@@ -353,7 +353,9 @@
     # Format logging
     setup_logging $CINDER_CONF $CINDER_USE_MOD_WSGI
 
-    write_uwsgi_config "$CINDER_UWSGI_CONF" "$CINDER_UWSGI" "/volume"
+    if is_service_enabled c-api; then
+        write_uwsgi_config "$CINDER_UWSGI_CONF" "$CINDER_UWSGI" "/volume"
+    fi
 
     if [[ -r $CINDER_PLUGINS/$CINDER_DRIVER ]]; then
         configure_cinder_driver