iio: adc: meson: remove unused timestamp channel

Remove IIO_CHAN_SOFT_TIMESTAMP channel because it's used only for
buffering mode which is not implemented.
Signed-off-by: George Stark <GNStark@sberdevices.ru>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230714114010.293440-2-gnstark@sberdevices.ruSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/meson_saradc.c

@@ -211,7 +211,6 @@ static const struct iio_chan_spec meson_sar_adc_iio_channels[] = {
 	MESON_SAR_ADC_CHAN(5),
 	MESON_SAR_ADC_CHAN(6),
 	MESON_SAR_ADC_CHAN(7),
-	IIO_CHAN_SOFT_TIMESTAMP(8),
 };
 
 static const struct iio_chan_spec meson_sar_adc_and_temp_iio_channels[] = {
@@ -224,7 +223,6 @@ static const struct iio_chan_spec meson_sar_adc_and_temp_iio_channels[] = {
 	MESON_SAR_ADC_CHAN(6),
 	MESON_SAR_ADC_CHAN(7),
 	MESON_SAR_ADC_TEMP_CHAN(8),
-	IIO_CHAN_SOFT_TIMESTAMP(9),
 };
 
 enum meson_sar_adc_avg_mode {