KVM: change kvm_assign_device() to print return value when iommu_attach_device() fails

Change existing kernel error message to include return value from
iommu_attach_device() when it fails. This will help debug device
assignment failures more effectively.
Signed-off-by: NShuah Khan <shuah.khan@hp.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

virt/kvm/iommu.c

@@ -168,11 +168,7 @@ int kvm_assign_device(struct kvm *kvm,
 
 	r = iommu_attach_device(domain, &pdev->dev);
 	if (r) {
-		printk(KERN_ERR "assign device %x:%x:%x.%x failed",
-			pci_domain_nr(pdev->bus),
-			pdev->bus->number,
-			PCI_SLOT(pdev->devfn),
-			PCI_FUNC(pdev->devfn));
+		dev_err(&pdev->dev, "kvm assign device failed ret %d", r);
 		return r;
 	}