ns2: move link layer type into NSE

Even it was in theory possible to mix NS-VC ll types within
a NSE. This is an unrealistic configuration.
Further more to select the correct load sharing mechanism
the NSE must know the correct link layer.

Change-Id: I18dfd40a2429cd61b7c4a3dad5f226c64296f7d8
diff --git a/src/gb/gprs_ns2_frgre.c b/src/gb/gprs_ns2_frgre.c
index cd478d6..3c276bc 100644
--- a/src/gb/gprs_ns2_frgre.c
+++ b/src/gb/gprs_ns2_frgre.c
@@ -555,6 +555,7 @@
 	}
 
 	bind->driver = &vc_driver_frgre;
+	bind->ll = GPRS_NS2_LL_FR_GRE;
 	bind->send_vc = frgre_vc_sendmsg;
 	bind->free_vc = free_vc;
 	bind->nsi = nsi;