user_simtrace2: Stop using printf, use libosmocore logging

This way we have consistent logging from all parts of the code via
the common libosmocore logging infrastructure.

Change-Id: I9ace31d781dd3e50f9a5d9239bafa87a01abb0d6
diff --git a/src/debug.c b/src/debug.c
index 70c04d2..91c2f71 100644
--- a/src/debug.c
+++ b/src/debug.c
@@ -31,6 +31,11 @@
 		.loglevel = LOGL_DEBUG,
 		.enabled = 1,
 	},
+	[DST2] = {
+		.name = "DST2",
+		.loglevel = LOGL_INFO,
+		.enabled = 1,
+	},
 };
 
 const struct log_info log_info = {