sysmocom/defaults.conf: Fix recently changed node name

This node was changed recently but this file was not updated.

Change-Id: Id5df83a356579340259d9d02ebc621f298151599
diff --git a/sysmocom/defaults.conf b/sysmocom/defaults.conf
index 67c9c5d..af5c52c 100644
--- a/sysmocom/defaults.conf
+++ b/sysmocom/defaults.conf
@@ -101,7 +101,7 @@
   enable_pcap: false
   log_all_level: warning
 
-open5gsepc:
+open5gs:
   db_host: "localhost"
 
 amarisoft: