iio: accel: sca3000: use devm_iio_kfifo_buffer_setup() helper

This change makes use of the devm_iio_kfifo_buffer_setup() helper, however
the unwind order is changed.
The life-time of the kfifo object is attached to the parent device object.
This is to make the driver a bit more consistent with the other IIO
drivers, even though (as it is now before this change) it shouldn't be a
problem.
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20210215104043.91251-5-alexandru.ardelean@analog.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/accel/sca3000.c

@@ -1272,20 +1272,6 @@ static int sca3000_write_event_config(struct iio_dev *indio_dev,
 	return ret;
 }
 
-static int sca3000_configure_ring(struct iio_dev *indio_dev)
-{
-	struct iio_buffer *buffer;
-
-	buffer = devm_iio_kfifo_allocate(&indio_dev->dev);
-	if (!buffer)
-		return -ENOMEM;
-
-	iio_device_attach_buffer(indio_dev, buffer);
-	indio_dev->modes |= INDIO_BUFFER_SOFTWARE;
-
-	return 0;
-}
-
 static inline
 int __sca3000_hw_ring_state_set(struct iio_dev *indio_dev, bool state)
 {
@@ -1479,7 +1465,9 @@ static int sca3000_probe(struct spi_device *spi)
 	}
 	indio_dev->modes = INDIO_DIRECT_MODE;
 
-	ret = sca3000_configure_ring(indio_dev);
+	ret = devm_iio_kfifo_buffer_setup(&spi->dev, indio_dev,
+					  INDIO_BUFFER_SOFTWARE,
+					  &sca3000_ring_setup_ops);
 	if (ret)
 		return ret;
 
@@ -1493,7 +1481,6 @@ static int sca3000_probe(struct spi_device *spi)
 		if (ret)
 			return ret;
 	}
-	indio_dev->setup_ops = &sca3000_ring_setup_ops;
 	ret = sca3000_clean_setup(st);
 	if (ret)
 		goto error_free_irq;