fix meta/salt with missing pillar

Change-Id: I5977edf0e691010cac695becf3634d864096f89e
diff --git a/sensu/meta/salt.yml b/sensu/meta/salt.yml
index 5937054..dac6991 100644
--- a/sensu/meta/salt.yml
+++ b/sensu/meta/salt.yml
@@ -10,7 +10,7 @@
     require:
     - salt: sensu.server
 grain:
-  {%- if pillar.sensu.client is defined %}
+  {%- if pillar.get('sensu', {}).get('client')%}
   {%- from "sensu/map.jinja" import client with context %}
   {%- set service_grains = {'sensu': {'check': {}}} %}
   {%- for service_name, service in pillar.items() %}