nvme-pci: don't fall back to a 32-bit DMA mask

Since Linux 5.0 drivers can safely set the largest DMA mask supported
by the device, and don't need fallbacks to work around the dma mapping
implementations.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>

drivers/nvme/host/pci.c

@@ -2289,8 +2289,7 @@ static int nvme_pci_enable(struct nvme_dev *dev)
 
 	pci_set_master(pdev);
 
-	if (dma_set_mask_and_coherent(dev->dev, DMA_BIT_MASK(64)) &&
-	    dma_set_mask_and_coherent(dev->dev, DMA_BIT_MASK(32)))
+	if (dma_set_mask_and_coherent(dev->dev, DMA_BIT_MASK(64)))
 		goto disable;
 
 	if (readl(dev->bar + NVME_REG_CSTS) == -1) {