LCLS: constify helper parameters

Related: OS#2487
Change-Id: I341f4ea172432b94e8e96919926a5fb6870c2a30
diff --git a/include/osmocom/bsc/osmo_bsc_lcls.h b/include/osmocom/bsc/osmo_bsc_lcls.h
index 3eaa589..c8b0ebd 100644
--- a/include/osmocom/bsc/osmo_bsc_lcls.h
+++ b/include/osmocom/bsc/osmo_bsc_lcls.h
@@ -29,7 +29,7 @@
 	LCLS_EV_OTHER_DEAD,
 };
 
-enum gsm0808_lcls_status lcls_get_status(struct gsm_subscriber_connection *conn);
+enum gsm0808_lcls_status lcls_get_status(const struct gsm_subscriber_connection *conn);
 
 void lcls_update_config(struct gsm_subscriber_connection *conn,
 			const uint8_t *config, const uint8_t *control);