ns2: move LL into public api

Also fix prefix. GPRS_NS -> GPRS_NS2.
In preparation to move LL into upper layer.

Change-Id: I3b5e0d51ce69b095095e5160ca0cf0d4534db1b8
diff --git a/src/gb/gprs_ns2_udp.c b/src/gb/gprs_ns2_udp.c
index 26a0483..38c1a16 100644
--- a/src/gb/gprs_ns2_udp.c
+++ b/src/gb/gprs_ns2_udp.c
@@ -391,7 +391,7 @@
 	priv = nsvc->priv;
 	priv->remote = *remote;
 
-	nsvc->ll = GPRS_NS_LL_UDP;
+	nsvc->ll = GPRS_NS2_LL_UDP;
 
 	return nsvc;
 }
@@ -403,7 +403,7 @@
 {
 	struct priv_bind *priv;
 
-	if (nsvc->ll != GPRS_NS_LL_UDP)
+	if (nsvc->ll != GPRS_NS2_LL_UDP)
 		return NULL;
 
 	if (nsvc->bind->driver != &vc_driver_ip)
@@ -420,7 +420,7 @@
 {
 	struct priv_vc *priv;
 
-	if (nsvc->ll != GPRS_NS_LL_UDP)
+	if (nsvc->ll != GPRS_NS2_LL_UDP)
 		return NULL;
 
 	priv = nsvc->priv;
@@ -442,7 +442,7 @@
 	struct priv_vc *vpriv;
 	struct priv_bind *bpriv;
 
-	if (nsvc->ll != GPRS_NS_LL_UDP)
+	if (nsvc->ll != GPRS_NS2_LL_UDP)
 		return false;
 
 	vpriv = nsvc->priv;