firewire: core: fix DMA unmapping in iso buffer removal

dmap_unmap_page() shall use the same direction as dma_map_page().

Signed-off-by: Stefan Richter <[e-mail]>

drivers/firewire/core-iso.c

···
 	for (j = 0; j < i; j++) {
 		address = page_private(buffer->pages[j]);
 		dma_unmap_page(card->device, address,
-			       PAGE_SIZE, DMA_TO_DEVICE);
+			       PAGE_SIZE, direction);
 		__free_page(buffer->pages[j]);
 	}
 	kfree(buffer->pages);
···
 	for (i = 0; i < buffer->page_count; i++) {
 		address = page_private(buffer->pages[i]);
 		dma_unmap_page(card->device, address,
-			       PAGE_SIZE, DMA_TO_DEVICE);
+			       PAGE_SIZE, buffer->direction);
 		__free_page(buffer->pages[i]);
 	}