Answering my own question. Added a file zephyr/nrf52dk_nrf52832.overlay with the content below. This is a device tree overlay for the underlying zephyr nrf52dk_nrf52832
board.
&uart0 {
status = "okay";
compatible = "nordic,nrf-uarte";
current-speed = <230400>;
tx-pin = <6>;
rx-pin = <8>;
};