net: enetc: Remove useless DMA-32 fallback configuration

As stated in [1], dma_set_mask() with a 64-bit mask never fails if
dev->dma_mask is non-NULL.
So, if it fails, the 32 bits case will also fail for the same reason.

Simplify code and remove some dead code accordingly.

[1]: https://lkml.org/lkml/2021/6/7/398

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/dbecd4eb49a9586ee343b5473dda4b84c42112e9.1641742884.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: tititiou36

drivers/net/ethernet/freescale/enetc/enetc.c

@@ -2897,12 +2897,8 @@ int enetc_pci_probe(struct pci_dev *pdev, const char *name, int sizeof_priv)
 	/* set up for high or low dma */
 	err = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
 	if (err) {
-		err = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
-		if (err) {
-			dev_err(&pdev->dev,
-				"DMA configuration failed: 0x%x\n", err);
-			goto err_dma;
-		}
+		dev_err(&pdev->dev, "DMA configuration failed: 0x%x\n", err);
+		goto err_dma;
 	}
 
 	err = pci_request_mem_regions(pdev, name);

drivers/net/ethernet/freescale/enetc/enetc_ptp.c

@@ -42,15 +42,10 @@ static int enetc_ptp_probe(struct pci_dev *pdev,
 	if (err)
 		return dev_err_probe(&pdev->dev, err, "device enable failed\n");
 
-	/* set up for high or low dma */
 	err = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
 	if (err) {
-		err = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
-		if (err) {
-			dev_err(&pdev->dev,
-				"DMA configuration failed: 0x%x\n", err);
-			goto err_dma;
-		}
+		dev_err(&pdev->dev, "DMA configuration failed: 0x%x\n", err);
+		goto err_dma;
 	}
 
 	err = pci_request_mem_regions(pdev, KBUILD_MODNAME);