enb_srs: add support for eNB traces

this patch adds support for srsENB event tracing. it provides
a cfg scenario to enable it.

Change-Id: Icb2342acac5db87a0889cbf1b6c7bb1ad26c16fa
diff --git a/sysmocom/scenarios/cfg-enb-tracing.conf b/sysmocom/scenarios/cfg-enb-tracing.conf
new file mode 100644
index 0000000..d8b373b
--- /dev/null
+++ b/sysmocom/scenarios/cfg-enb-tracing.conf
@@ -0,0 +1,3 @@
+config:
+  enb:
+    enable_tracing: true
\ No newline at end of file