gbproxy: Reset IMSI acquisition within gbproxy_unregister_link_info

Currently then link_info is not cleaned up completely, when
gbproxy_unregister_link_info is called.

This patch adds a function gbproxy_reset_link that must be defined
externally. This is done in gb_proxy.c, where it resets the IMSI
acquisition.

Sponsored-by: On-Waves ehf
diff --git a/openbsc/src/gprs/gb_proxy.c b/openbsc/src/gprs/gb_proxy.c
index 9aeb010..867364d 100644
--- a/openbsc/src/gprs/gb_proxy.c
+++ b/openbsc/src/gprs/gb_proxy.c
@@ -76,6 +76,7 @@
 			  uint16_t ns_bvci);
 static int gbprox_relay2sgsn(struct gbproxy_config *cfg, struct msgb *old_msg,
 			     uint16_t ns_bvci, uint16_t sgsn_nsei);
+static void gbproxy_reset_imsi_acquisition(struct gbproxy_link_info* link_info);
 
 static int check_peer_nsei(struct gbproxy_peer *peer, uint16_t nsei)
 {
@@ -273,6 +274,11 @@
 	return sgsn_tlli;
 }
 
+void gbproxy_reset_link(struct gbproxy_link_info *link_info)
+{
+	gbproxy_reset_imsi_acquisition(link_info);
+}
+
 /* Returns != 0 iff IMSI acquisition was in progress */
 static int gbproxy_restart_imsi_acquisition(struct gbproxy_link_info* link_info)
 {