mtip32xx: fix checks for dma mapping errors

exec_drive_taskfile() checks for dma mapping errors by comparison
returned address with zero, while pci_dma_mapping_error() should be used.

Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/block/mtip32xx/mtip32xx.c

@@ -2051,7 +2051,7 @@ static int exec_drive_taskfile(struct driver_data *dd,
 					 outbuf,
 					 taskout,
 					 DMA_TO_DEVICE);
-		if (outbuf_dma == 0) {
+		if (pci_dma_mapping_error(dd->pdev, outbuf_dma)) {
 			err = -ENOMEM;
 			goto abort;
 		}
@@ -2068,7 +2068,7 @@ static int exec_drive_taskfile(struct driver_data *dd,
 		inbuf_dma = pci_map_single(dd->pdev,
 					 inbuf,
 					 taskin, DMA_FROM_DEVICE);
-		if (inbuf_dma == 0) {
+		if (pci_dma_mapping_error(dd->pdev, inbuf_dma)) {
 			err = -ENOMEM;
 			goto abort;
 		}