fpga: dfl: afu: Pass the correct device to dma_mapping_error()

dma_mapping_error() was being called on a different device struct than
what was passed to map/unmap. Besides rendering the error checking
ineffective, it caused a debug splat with CONFIG_DMA_API_DEBUG.

Signed-off-by: Scott Wood <[e-mail]>
Acked-by: Wu Hao <[e-mail]>
Acked-by: Moritz Fischer <[e-mail]>
Acked-by: Alan Tull <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/fpga/dfl-afu-dma-region.c

···
 				    region->pages[0], 0,
 				    region->length,
 				    DMA_BIDIRECTIONAL);
-	if (dma_mapping_error(&pdata->dev->dev, region->iova)) {
+	if (dma_mapping_error(dfl_fpga_pdata_to_parent(pdata), region->iova)) {
 		dev_err(&pdata->dev->dev, "failed to map for dma\n");
 		ret = -EFAULT;
 		goto unpin_pages;