Yaniv,
These two functions seem to work. After the AD9361 is initialized, you have to configure the filters (ad9361_set_tx_fir_config(), ad9361_set_rx_fir_config()) and after that to enable them (ad9361_set_rx_fir_en_dis(), ad9361_set_tx_fir_en_dis()).
Regards,
Dragos