Provide configurations for the nRF52840 DK and nRF5340 DK boards.
Adjust the test to cover specifics of I2S peripherals on nRF SoCs
(need of starting RX and TX simultaneously, lack of internal loopback).
Signed-off-by: Andrzej Głąbek <andrzej.glabek@nordicsemi.no>
1. Provide an option to loopback over separate I2S ports
2. Increase the buffer count in the loopback test to 4
3. Update test_i2s_transfer_rx_overrun test on how to
handle RX overrun failures
Signed-off-by: Mahesh Mahadevan <mahesh.mahadevan@nxp.com>