Bluetooth: audio: BAP: set the past_avail status

While refactoring the handling of callbacks the setting of past_avail
status got deleted (and it was in the wrong place). Adding it back at
the correct place.

Signed-off-by: Andries Kruithof <andries.kruithof@nordicsemi.no>

subsys/bluetooth/audio/bap_broadcast_assistant.c

@@ -430,6 +430,7 @@ static uint8_t notify_handler(struct bt_conn *conn,
 			return parse_and_send_recv_state(conn, handle, data, length, &recv_state);
 		}
 	} else {
+		broadcast_assistant.past_avail[index] = false;
 		bap_broadcast_assistant_recv_state_removed(conn, 0,
 							   broadcast_assistant.src_ids[index]);
 	}