gbproxy: Replace NS-VC references by NSEI

Currently in most places in gb_proxy.c a reference to a NS-VC object
is used where the peer is meant instead. The patch changes this by
using the NSEI instead in these cases.

Sponsored-by: On-Waves ehf
diff --git a/openbsc/tests/gbproxy/gbproxy_test.c b/openbsc/tests/gbproxy/gbproxy_test.c
index 6e7be64..0b4521f 100644
--- a/openbsc/tests/gbproxy/gbproxy_test.c
+++ b/openbsc/tests/gbproxy/gbproxy_test.c
@@ -160,7 +160,7 @@
 
 	switch (event) {
 	case GPRS_NS_EVT_UNIT_DATA:
-		return gbprox_rcvmsg(msg, nsvc, bvci);
+		return gbprox_rcvmsg(msg, nsvc->nsei, bvci, nsvc->nsvci);
 	default:
 		break;
 	}