add gsm0808_create_handover_request_ack()

Related: OS#2283 (inter-BSC Handover, BSC side, MT)
Change-Id: I692292a06c7d66004404560dc4ed933ca9107f9b
diff --git a/include/osmocom/gsm/gsm0808.h b/include/osmocom/gsm/gsm0808.h
index 4f239e6..5c03400 100644
--- a/include/osmocom/gsm/gsm0808.h
+++ b/include/osmocom/gsm/gsm0808.h
@@ -117,6 +117,10 @@
 };
 struct msgb *gsm0808_create_handover_required(const struct gsm0808_handover_required *params);
 
+struct msgb *gsm0808_create_handover_request_ack(const uint8_t *l3_info, uint8_t l3_info_len,
+						 uint8_t chosen_channel, uint8_t chosen_encr_alg,
+						 uint8_t chosen_speech_version);
+
 struct msgb *gsm0808_create_dtap(struct msgb *msg, uint8_t link_id);
 void gsm0808_prepend_dtap_header(struct msgb *msg, uint8_t link_id);