iio: adc: ti-ads8688: add missing select IIO_(TRIGGERED_)BUFFER in Kconfig

This driver makes use of triggered buffers, but does not select the
required modules.

Fixes: 2a864877 ("iio: adc: ti-ads8688: add trigger and buffer support")
Add the missing 'select IIO_BUFFER' and 'select IIO_TRIGGERED_BUFFER'.
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Reviewed-by: Sean Nyekjaer <sean@geanix.com>
Link: https://patch.msgid.link/20241003-iio-select-v1-4-67c0385197cd@gmail.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/Kconfig

@@ -1483,6 +1483,8 @@ config TI_ADS8344
 config TI_ADS8688
 	tristate "Texas Instruments ADS8688"
 	depends on SPI
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
 	help
 	  If you say yes here you get support for Texas Instruments ADS8684 and
 	  and ADS8688 ADC chips