kvm: KVM_CAP_IOMMU only available with device assignment

Fix build with CONFIG_PCI unset by linking KVM_CAP_IOMMU to
device assignment config option.  It has no purpose otherwise.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

arch/ia64/kvm/kvm-ia64.c

@@ -204,9 +204,11 @@ int kvm_dev_ioctl_check_extension(long ext)
 	case KVM_CAP_COALESCED_MMIO:
 		r = KVM_COALESCED_MMIO_PAGE_OFFSET;
 		break;
+#ifdef CONFIG_KVM_DEVICE_ASSIGNMENT
 	case KVM_CAP_IOMMU:
 		r = iommu_present(&pci_bus_type);
 		break;
+#endif
 	default:
 		r = 0;
 	}