iio: adc: ad7944: Drop pwm time unit specification

Having the pwm configuration specified in nano seconds is the default
and upstream behaviour and there is ongoing work to remove other time
units. So just drop the explicit specification of the default to allow
removing the .time_unit member from struct pwm_state.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>

Author: ukleinek

drivers/iio/adc/ad7944.c

@@ -735,7 +735,6 @@ static int ad7944_probe(struct spi_device *spi)
 			.period = NSEC_PER_SEC / AD7944_DEFAULT_SAMPLE_FREQ_HZ,
 			.duty_cycle = AD7944_PWM_TRIGGER_DUTY_CYCLE_NS,
 			.enabled = true,
-			.time_unit = PWM_UNIT_NSEC,
 		};
 
 		adc->pwm = devm_pwm_get(dev, NULL);