gprs_ns2_vc_fsm: in RESET accept RESET as ACK

When both side sends RESET at the same time 48.016

Change-Id: I49d2a4f257f45b7bc4f0a7a6c5b8381071893686
diff --git a/src/gb/gprs_ns2_vc_fsm.c b/src/gb/gprs_ns2_vc_fsm.c
index 60c46e6..04d95f4 100644
--- a/src/gb/gprs_ns2_vc_fsm.c
+++ b/src/gb/gprs_ns2_vc_fsm.c
@@ -272,6 +272,9 @@
 
 	if (priv->initiate_reset) {
 		switch (event) {
+		case GPRS_NS2_EV_RX_RESET:
+			ns2_tx_reset_ack(priv->nsvc);
+			/* fall-through */
 		case GPRS_NS2_EV_RX_RESET_ACK:
 			osmo_fsm_inst_state_chg(fi, GPRS_NS2_ST_BLOCKED,
 						nsi->timeout[NS_TOUT_TNS_BLOCK], NS_TOUT_TNS_BLOCK);