iio: kfifo: un-export devm_iio_kfifo_allocate() function

At this point all drivers should use devm_iio_kfifo_buffer_setup() instead
of manually allocating via devm_iio_kfifo_allocate() and assigning ops and
modes.

With this change, the devm_iio_kfifo_allocate() will be made private to the
IIO core, since all drivers should call either
devm_iio_kfifo_buffer_setup() or devm_iio_triggered_buffer_setup() to
create a kfifo buffer.
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20210215104043.91251-6-alexandru.ardelean@analog.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/driver-api/driver-model/devres.rst

@@ -285,7 +285,6 @@ I2C
 IIO
   devm_iio_device_alloc()
   devm_iio_device_register()
-  devm_iio_kfifo_allocate()
   devm_iio_kfifo_buffer_setup()
   devm_iio_triggered_buffer_setup()
   devm_iio_trigger_alloc()

drivers/iio/buffer/kfifo_buf.c

@@ -186,7 +186,7 @@ static void devm_iio_kfifo_release(struct device *dev, void *res)
  * RETURNS:
  * Pointer to allocated iio_buffer on success, NULL on failure.
  */
-struct iio_buffer *devm_iio_kfifo_allocate(struct device *dev)
+static struct iio_buffer *devm_iio_kfifo_allocate(struct device *dev)
 {
 	struct iio_buffer **ptr, *r;
 
@@ -204,7 +204,6 @@ struct iio_buffer *devm_iio_kfifo_allocate(struct device *dev)
 
 	return r;
 }
-EXPORT_SYMBOL(devm_iio_kfifo_allocate);
 
 /**
  * devm_iio_kfifo_buffer_setup - Allocate a kfifo buffer & attach it to an IIO device

include/linux/iio/kfifo_buf.h

@@ -10,8 +10,6 @@ struct device;
 struct iio_buffer *iio_kfifo_allocate(void);
 void iio_kfifo_free(struct iio_buffer *r);
 
-struct iio_buffer *devm_iio_kfifo_allocate(struct device *dev);
-
 int devm_iio_kfifo_buffer_setup(struct device *dev,
 				struct iio_dev *indio_dev,
 				int mode_flags,