iu_client: introduce ranap_iu_free_ue() to free the UE connections

When freeing the UE connection object, disconnect the SCCP connection.

Change-Id: I6812edb4da487507ccf9f483de801c1c65c4b72b
diff --git a/include/osmocom/ranap/iu_client.h b/include/osmocom/ranap/iu_client.h
index 873b2d2..0cb84da 100644
--- a/include/osmocom/ranap/iu_client.h
+++ b/include/osmocom/ranap/iu_client.h
@@ -70,5 +70,9 @@
 int ranap_iu_tx_common_id(struct ranap_ue_conn_ctx *ue_ctx, const char *imsi);
 int ranap_iu_tx_release(struct ranap_ue_conn_ctx *ctx, const struct RANAP_Cause *cause);
 
+/* freeing the UE will release all resources
+ * This will close the SCCP connection connected to the UE */
+void ranap_iu_free_ue(struct ranap_ue_conn_ctx *ue_ctx);
+
 void ranap_iu_vty_init(int iu_parent_node, enum ranap_nsap_addr_enc *rab_assign_addr_enc);
 int ranap_iu_vty_config_write(struct vty *vty, const char *indent);