Added double quote to prevent telegraf startup failure

Change-Id: Ibc2b3416c5c508096d2c6304b99808e766504f0a
Closes-Bug: PROD-19586
diff --git a/keepalived/files/telegraf.conf b/keepalived/files/telegraf.conf
index 47c2022..1ab05a2 100644
--- a/keepalived/files/telegraf.conf
+++ b/keepalived/files/telegraf.conf
@@ -1,6 +1,6 @@
 [[inputs.ipcheck]]
 {%- include 'telegraf/files/input/_common.conf' %}
 {%- if values.interface_name_regexp_exclude is defined %}
-  interface_name_regexp_exclude = {{ values.interface_name_regexp_exclude }}
+  interface_name_regexp_exclude = "{{ values.interface_name_regexp_exclude }}"
 {%- endif %}
 {%- include 'telegraf/files/input/_tags.conf' %}