send the RAT type (GERAN-A / UTRAN-Iu) to HLR on LU

Use new OSMO_GSUP_RAT_TYPES_IE to transmit the subscriber's RAT type to the
HLR.

Depends: I3e399ca8a85421f77a9a15e608413d1507722955 (osmo-hlr)
Change-Id: I70641d6eaddddbfbb5d7b7bfb86d27e0bcbeff72

src/gprs/gprs_subscriber.c

@@ -820,6 +820,13 @@ int gprs_subscr_location_update(struct gprs_subscr *subscr)
 		"subscriber data is not available\n");
 
 	gsup_msg.message_type = OSMO_GSUP_MSGT_UPDATE_LOCATION_REQUEST;
+#if BUILD_IU
+	if (subscr->sgsn_data->mm->ran_type == MM_CTX_T_UTRAN_Iu)
+		gsup_msg.rat_types[0] = OSMO_RAT_UTRAN_IU;
+	else
+#endif
+		gsup_msg.rat_types[0] = OSMO_RAT_GERAN_A;
+	gsup_msg.rat_types_len = 1;
 	return gprs_subscr_tx_gsup_message(subscr, &gsup_msg);
 }