misc: pci_endpoint_test: Refactor dma_set_mask_and_coherent() logic

dma_set_mask_and_coherent() should never fail when the mask is >= 32bit,
unless the architecture has no DMA support. So no need to check for the
error and also no need to set dma_set_mask_and_coherent(32) as a fallback.

Even if dma_set_mask_and_coherent(48) fails due to the lack of DMA support
(theoretically), then dma_set_mask_and_coherent(32) will also fail for the
same reason. So the fallback doesn't make sense.

Simplify the code by setting the streaming and coherent DMA mask to 48
bits.

Link: https://lore.kernel.org/linux-pci/20240502195903.3191049-1-Frank.Li@nxp.comSigned-off-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Niklas Cassel <cassel@kernel.org>

drivers/misc/pci_endpoint_test.c

@@ -857,11 +857,7 @@ static int pci_endpoint_test_probe(struct pci_dev *pdev,
 	init_completion(&test->irq_raised);
 	mutex_init(&test->mutex);
 
-	if ((dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(48)) != 0) &&
-	    dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32)) != 0) {
-		dev_err(dev, "Cannot set DMA mask\n");
-		return -EINVAL;
-	}
+	dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(48));
 
 	err = pci_enable_device(pdev);
 	if (err) {