For uart_async_api, uart_mix_fifo_poll & uart_pm:
These test can be run fine in the simulated nrf52_bsim board,
just connecting the UART Tx and Rx in loopback,
but we need an overlay just like for the real boards.
Let's provide it.
Signed-off-by: Alberto Escolar Piedras <alberto.escolar.piedras@nordicsemi.no>
Unify set of the pins on `nrf52840dk_nrf52840`, which is used by
`gpio_loopback` fixture.
Signed-off-by: Katarzyna Giądła <katarzyna.giadla@nordicsemi.no>
Added test which validates that uart device correctly handles
going to and from low power state.
Signed-off-by: Krzysztof Chruscinski <krzysztof.chruscinski@nordicsemi.no>
