ns2: message: BLOCK/BLOCK ACK allow to use a given NSVCI instead of using the nsvc nsvci

The BLOCK and BLOCK ACK PDUs can be send over a working NSVC to inform
the NSE that a NSVC is blocked.

Change-Id: I6189229fdc1f054e86811bc60cb7646e1f758a78
diff --git a/src/gb/gprs_ns2_internal.h b/src/gb/gprs_ns2_internal.h
index bfb12d9..a5d78d4 100644
--- a/src/gb/gprs_ns2_internal.h
+++ b/src/gb/gprs_ns2_internal.h
@@ -422,8 +422,8 @@
 		   unsigned int num_ip6_elems);
 
 /* transmit message over a VC */
-int ns2_tx_block(struct gprs_ns2_vc *nsvc, uint8_t cause);
-int ns2_tx_block_ack(struct gprs_ns2_vc *nsvc);
+int ns2_tx_block(struct gprs_ns2_vc *nsvc, uint8_t cause, uint16_t *nsvci);
+int ns2_tx_block_ack(struct gprs_ns2_vc *nsvc, uint16_t *nsvci);
 
 int ns2_tx_reset(struct gprs_ns2_vc *nsvc, uint8_t cause);
 int ns2_tx_reset_ack(struct gprs_ns2_vc *nsvc);