Revert "virtio: unbreak virtio-pci with IOMMU after caching ring translations"

This reverts commit
96a8821d. Previous patch is a better
solution which does not require a strict order between virtio and IOMMU.

CC: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NJason Wang <jasowang@redhat.com>

hw/virtio/virtio-pci.c

@@ -1153,7 +1153,7 @@ static AddressSpace *virtio_pci_get_dma_as(DeviceState *d)
     VirtIOPCIProxy *proxy = VIRTIO_PCI(d);
     PCIDevice *dev = &proxy->pci_dev;
 
-    return pci_device_iommu_address_space(dev);
+    return pci_get_address_space(dev);
 }
 
 static int virtio_pci_add_mem_cap(VirtIOPCIProxy *proxy,