Fix meta grains merging

Change-Id: I9c9cdefb9ccfde3ee52c11ac2bf21c946f1e8e47
diff --git a/fluentd/map.jinja b/fluentd/map.jinja
index 1ced2a0..95bcd72 100644
--- a/fluentd/map.jinja
+++ b/fluentd/map.jinja
@@ -29,4 +29,4 @@
 {%- endfor %}
 
 {# Deep-merge the service configuration with the pillar data #}
-{%- do salt['defaults.merge'](fluentd_agent, fluentd_grains) %}
+{%- do salt['defaults.merge'](fluentd_agent, fluentd_grains.get('agent', {})) %}