iio: buffer-dmaengine: use %zu specifier for sprintf(align)

The 'size_t' type behaves differently on 64-bit architectures, and causes
compiler a warning of the sort "format '%u' expects argument of type
'unsigned int', but argument 3 has type 'size_t {aka long unsigned int}'".

This change adds the correct specifier for the 'align' field.

Fixes: 4538c185 ("iio: buffer-dmaengine: Report buffer length requirements")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

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

@@ -134,7 +134,7 @@ static ssize_t iio_dmaengine_buffer_get_length_align(struct device *dev,
 	struct dmaengine_buffer *dmaengine_buffer =
 		iio_buffer_to_dmaengine_buffer(indio_dev->buffer);
 
-	return sprintf(buf, "%u\n", dmaengine_buffer->align);
+	return sprintf(buf, "%zu\n", dmaengine_buffer->align);
 }
 
 static IIO_DEVICE_ATTR(length_align_bytes, 0444,