GATTS_HandleValueIndication() function

* Function GATTs_HandleValueIndication * Description This function sends a handle value indication to a client. * Parameter conn_id: connection identifier. * attr_handle: Attribute handle of this handle value indication. * val_len: Length of the indicated attribute value. * p_val: Pointer to the indicated attribute value data. * Returns GATT_SUCCESS if successfully sent or queued; otherwise error code.