ad9361: Implemented ad9361_get_rx_fir_config() and ad9361_get_tx_fir_config().
ad9361: Implemented dds_get_frequency(), dds_get_phase(), dds_get_scale() and dac_get_datasel().
ad9361: Implemented ad9361_get_bist_loopback(), ad9361_get_bist_prbs() and ad9361_get_bist_tone().