iio: buffer-dmaengine: make use of the 'struct device *' argument

Respect the @dev argument in devm_iio_dmaengine_buffer_setup() and bind the
IIO DMA buffer lifetime to that device.

For the only user of this function, the IIO parent device is the
struct device being passed to the API so no real fix in here (just
consistency with other IIO APIs).

Signed-off-by: Nuno Sa <[e-mail]>
Reviewed-by: David Lechner <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/buffer/industrialio-buffer-dmaengine.c

···
 {
 	struct iio_buffer *buffer;
 
-	buffer = devm_iio_dmaengine_buffer_alloc(indio_dev->dev.parent,
-						 channel);
+	buffer = devm_iio_dmaengine_buffer_alloc(dev, channel);
 	if (IS_ERR(buffer))
 		return PTR_ERR(buffer);