Aether-1359 - Add the serviceMonitor so that prometheus know how to scrape dbuf's metric

Change-Id: Ie067a408b4410149ef18d5636b0cb8bef6a82a1c
diff --git a/apps/dbuf/values.yaml b/apps/dbuf/values.yaml
index 2b3e261..1beeaa5 100644
--- a/apps/dbuf/values.yaml
+++ b/apps/dbuf/values.yaml
@@ -48,6 +48,7 @@
   port: 2152
   interface: "net0"
 
+prometheus_enable: true
 service:
   stats:
     port: 8080