msc_a.c, CC trans: change a comment to a debug log

Change-Id: I5a3cc6219080910119b0c9ff11fc2b9eb96a06e5
diff --git a/src/libmsc/msc_a.c b/src/libmsc/msc_a.c
index b3e2e32..a082cb8 100644
--- a/src/libmsc/msc_a.c
+++ b/src/libmsc/msc_a.c
@@ -1653,7 +1653,7 @@
 	OSMO_ASSERT(cc_trans->type == TRANS_CC);
 
 	if (msc_a->cc.active_trans == cc_trans) {
-		/* Assignment for this trans already started earlier. */
+		LOG_MSC_A(msc_a, LOGL_DEBUG, "Assignment for this trans already started earlier\n");
 		return 0;
 	}