ns2: fsm: add comment don't answer on a STATUS with a STATUS

Change-Id: Ib8f700f9193a96a7bada3b0293dcecf6a05d6efc
diff --git a/src/gb/gprs_ns2_vc_fsm.c b/src/gb/gprs_ns2_vc_fsm.c
index a366c93..d09c31a 100644
--- a/src/gb/gprs_ns2_vc_fsm.c
+++ b/src/gb/gprs_ns2_vc_fsm.c
@@ -861,6 +861,7 @@
 	/* TODO: handle BLOCK/UNBLOCK/ALIVE with different VCI */
 
 	if (ns2_validate(nsvc, nsh->pdu_type, msg, tp, &cause)) {
+		/* don't answer on a STATUS with a STATUS */
 		if (nsh->pdu_type != NS_PDUT_STATUS) {
 			rc = ns2_tx_status(nsvc, cause, 0, msg);
 			goto out;