x86, amd-iommu: propagate PCI device enabling error

propagate an error in enabling the PCI device.

Also eliminates this warning:

 arch/x86/kernel/amd_iommu_init.c: In function ‘init_iommu_one’:
 arch/x86/kernel/amd_iommu_init.c:726: warning: ignoring return value of ‘pci_enable_device’, declared with attribute warn_unused_result
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/amd_iommu_init.c

@@ -723,9 +723,7 @@ static int __init init_iommu_one(struct amd_iommu *iommu, struct ivhd_header *h)
 	init_iommu_from_acpi(iommu, h);
 	init_iommu_devices(iommu);
 
-	pci_enable_device(iommu->dev);
-
-	return 0;
+	return pci_enable_device(iommu->dev);
 }
 
 /*