PCI: Remove unused attr variable in pci_dma_configure

Clang warns:

drivers/pci/pci-driver.c:1603:21: error: unused variable 'attr'
[-Werror,-Wunused-variable]

Commit e5361ca2 ("ACPI / scan: Refactor _CCA enforcement") removed
attr's use and replaced it with its assigned value so it is no longer
needed.
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/pci/pci-driver.c

@@ -1600,7 +1600,6 @@ static int pci_dma_configure(struct device *dev)
 		ret = of_dma_configure(dev, bridge->parent->of_node, true);
 	} else if (has_acpi_companion(bridge)) {
 		struct acpi_device *adev = to_acpi_device_node(bridge->fwnode);
-		enum dev_dma_attr attr = acpi_get_dma_attr(adev);
 
 		ret = acpi_dma_configure(dev, acpi_get_dma_attr(adev));
 	}