gtp-kernel: Fix tunnel creation/removal for GTP Version 1

When Linux Kernel GTP-U support is enabled, OpenGGSN so far only worked
with GTPv0,but not with GTPv1, as the TEI values were not correctly
configured.  This patch fixes the initialzation of the local and remote
TEI before using libgtpnl to create a tunnel context in the kernel.

Change-Id: I3e953ff5b4ab44c26dbbe20d18b61038fa57ff32
diff --git a/ggsn/gtp-kernel.c b/ggsn/gtp-kernel.c
index 93dea23..dbe5a9f 100644
--- a/ggsn/gtp-kernel.c
+++ b/ggsn/gtp-kernel.c
@@ -192,7 +192,10 @@
 		gtp_tunnel_set_tid(t, pdp_gettid(pdp->imsi, pdp->nsapi));
 		gtp_tunnel_set_flowid(t, pdp->flru);
 	} else {
-		gtp_tunnel_set_tid(t, pdp->teid_gn); /* GTPIE_TEI_DI */
+		gtp_tunnel_set_i_tei(t, pdp->teid_own);
+		/* use the TEI advertised by SGSN when sending packets
+		 * towards the SGSN */
+		gtp_tunnel_set_o_tei(t, pdp->teid_gn);
 	}
 
 	ret = gtp_add_tunnel(gtp_nl.genl_id, gtp_nl.nl, t);
@@ -221,7 +224,7 @@
 		gtp_tunnel_set_tid(t, pdp_gettid(pdp->imsi, pdp->nsapi));
 		gtp_tunnel_set_flowid(t, pdp->flru);
 	} else {
-		gtp_tunnel_set_tid(t, pdp->teid_gn); /* GTPIE_TEI_DI */
+		gtp_tunnel_set_i_tei(t, pdp->teid_own);
 	}
 
 	ret = gtp_del_tunnel(gtp_nl.genl_id, gtp_nl.nl, t);