bts: f_validate_si_scheduling(): Print correct TC value

We always claimed "No SI messages for TC=0" even in cases where
TC is actually a different value.

Change-Id: I53e357c21b3f1090e4e396e292fcd193581d5bb8
diff --git a/bts/BTS_Tests.ttcn b/bts/BTS_Tests.ttcn
index 83688b9..e0e8ac4 100644
--- a/bts/BTS_Tests.ttcn
+++ b/bts/BTS_Tests.ttcn
@@ -1371,7 +1371,7 @@
 	var integer i;
 	for (i := 0; i < sizeof(si_per_tc); i := i + 1) {
 		if (sizeof(si_per_tc[i]) == 0) {
-			setverdict(fail, "No SI messages for TC=0!");
+			setverdict(fail, "No SI messages for TC=", i);
 		}
 	}
 	if (cfg.si1_present) {