gsm: Support Sending Last EUTRAN PLMN Id in Handover Required

Related: SYS#5337
Change-Id: I6280ce1abc283f1491bc6f391b2dd952df33a16b
diff --git a/include/osmocom/gsm/gsm0808.h b/include/osmocom/gsm/gsm0808.h
index b921eda..ecb9827 100644
--- a/include/osmocom/gsm/gsm0808.h
+++ b/include/osmocom/gsm/gsm0808.h
@@ -126,6 +126,9 @@
 		uint8_t field;
 	} current_channel_type_2;
 
+	bool last_eutran_plmn_id_present;
+	struct osmo_plmn_id last_eutran_plmn_id;
+
 	/* more items are defined in the spec and may be added later */
 	bool more_items; /*< always set this to false */
 };