i2c: ismt: 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/2021/6/7/398Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Seth Heasley <seth.heasley@intel.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

drivers/i2c/busses/i2c-ismt.c

@@ -937,11 +937,8 @@ ismt_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 
 	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_set_mask fail\n");
-			return -ENODEV;
-		}
+		dev_err(&pdev->dev, "dma_set_mask fail\n");
+		return -ENODEV;
 	}
 
 	err = ismt_dev_init(priv);