staging:iio:impedance-analyzer switch from sw_ring to kfifo.

sw_ring buffer implementation is going away so switch to the
kfifo based alternative.

Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/staging/iio/impedance-analyzer/Kconfig

···
 	tristate "Analog Devices AD5933, AD5934 driver"
 	depends on I2C
 	select IIO_BUFFER
-	select IIO_SW_RING
+	select IIO_KFIFO_BUF
 	help
 	  Say yes here to build support for Analog Devices Impedance Converter,
 	  Network Analyzer, AD5933/4, provides direct access via sysfs.

drivers/staging/iio/impedance-analyzer/ad5933.c

···
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
 #include <linux/iio/buffer.h>
-#include "../ring_sw.h"
+#include <linux/iio/kfifo_buf.h>
 
 #include "ad5933.h"
 
···
 
 static int ad5933_register_ring_funcs_and_init(struct iio_dev *indio_dev)
 {
-	indio_dev->buffer = iio_sw_rb_allocate(indio_dev);
+	indio_dev->buffer = iio_kfifo_allocate(indio_dev);
 	if (!indio_dev->buffer)
 		return -ENOMEM;
 
···
 error_uninitialize_ring:
 	iio_buffer_unregister(indio_dev);
 error_unreg_ring:
-	iio_sw_rb_free(indio_dev->buffer);
+	iio_kfifo_free(indio_dev->buffer);
 error_disable_reg:
 	if (!IS_ERR(st->reg))
 		regulator_disable(st->reg);
···
 
 	iio_device_unregister(indio_dev);
 	iio_buffer_unregister(indio_dev);
-	iio_sw_rb_free(indio_dev->buffer);
+	iio_kfifo_free(indio_dev->buffer);
 	if (!IS_ERR(st->reg)) {
 		regulator_disable(st->reg);
 		regulator_put(st->reg);