fix meta/salt with missing pillar

Change-Id: I714a6ecfe3d4e3014d31bf4009dd3e6fc46bc86e
diff --git a/grafana/meta/salt.yml b/grafana/meta/salt.yml
index b809aed..50c001f 100644
--- a/grafana/meta/salt.yml
+++ b/grafana/meta/salt.yml
@@ -1,4 +1,4 @@
-{%- if pillar.grafana.collector is defined %}
+{%- if pillar.get('grafana', {}).get('collector') %}
   {%- if pillar.grafana.collector.get('enabled', False) %}
     {%- set service_grains = {} %}
     {%- for service_name, service in pillar.iteritems() %}