Bluetooth: BAP: Scan delegator: Add log if actionable CBs are not set

If the callbacks are not set, then we cannot do the requested actions
from the broadcast assistant. Since this is a significant issue,
that may prevent the role from working as intended,
LOG_WRN is used other LOG_DBG.

Signed-off-by: Emil Gydesen <emil.gydesen@nordicsemi.no>

subsys/bluetooth/audio/bap_scan_delegator.c

@@ -249,6 +249,8 @@ static void bis_sync_request_updated(struct bt_conn *conn,
 	    scan_delegator_cbs->bis_sync_req != NULL) {
 		scan_delegator_cbs->bis_sync_req(conn, &internal_state->state,
 						 internal_state->requested_bis_sync);
+	} else {
+		LOG_WRN("bis_sync_req callback is missing");
 	}
 }
 
@@ -469,6 +471,8 @@ static int pa_sync_request(struct bt_conn *conn,
 		err = scan_delegator_cbs->pa_sync_req(conn, state,
 						      past_supported,
 						      pa_interval);
+	} else {
+		LOG_WRN("pa_sync_req callback is missing, rejecting PA sync request");
 	}
 
 	return err;
@@ -482,6 +486,8 @@ static int pa_sync_term_request(struct bt_conn *conn,
 	if (scan_delegator_cbs != NULL &&
 	    scan_delegator_cbs->pa_sync_req != NULL) {
 		err = scan_delegator_cbs->pa_sync_term_req(conn, state);
+	} else {
+		LOG_WRN("pa_sync_term_req callback is missing, rejecting PA sync term request");
 	}
 
 	return err;