iio: chemical: sps30: fix missing triggered buffer dependency

SPS30 uses triggered buffer, but the dependency is not specified in the
Kconfig file.  Fix this by selecting IIO_BUFFER and IIO_TRIGGERED_BUFFER
config symbols.

Cc: stable@vger.kernel.org
Fixes: 232e0f6 ("iio: chemical: add support for Sensirion SPS30 sensor")
Signed-off-by: Petr Štetiar <ynezz@true.cz>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/chemical/Kconfig

@@ -91,6 +91,8 @@ config SPS30
 	tristate "SPS30 particulate matter sensor"
 	depends on I2C
 	select CRC8
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
 	help
 	  Say Y here to build support for the Sensirion SPS30 particulate
 	  matter sensor.