Grafana prevent yaml from failing

When including /meta/salt.yml from outside of this
formula the yaml can fail if appropriate pillar elements are not
found. Changing syntax to eliminate this. Including the file
above is needed for generating minion orchestration config
for future use with salt orchestration methods

Change-Id: Ia3fb7eee7c6298d294f641232c8c7e8f8b5806af
Related-PROD: PROD-19973
diff --git a/grafana/meta/salt.yml b/grafana/meta/salt.yml
index 50c001f..3c00ab7 100644
--- a/grafana/meta/salt.yml
+++ b/grafana/meta/salt.yml
@@ -17,7 +17,7 @@
 {%- endif %}
 
 minion:
-  {%- if pillar.grafana.client is defined %}
+  {%- if pillar.get('grafana', {}).client is defined %}
   grafana:
     {%- from "grafana/map.jinja" import client with context %}
     grafana_version: {{ client.server.get('version', 3) }}