Revert "virtio: Add PCI memory BAR in addition to PIO BAR"

This reverts commit 46d95bfec7f9429d5228078219413d7e33496d65.

hw/virtio-pci.c

diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c
index 83a4b35..ca5923c 100644
--- a/hw/virtio-pci.c
+++ b/hw/virtio-pci.c
@@ -654,8 +654,6 @@
                           "virtio-pci", size);
     pci_register_bar(&proxy->pci_dev, 0, PCI_BASE_ADDRESS_SPACE_IO,
                      &proxy->bar);
-    pci_register_bar(&proxy->pci_dev, 2, PCI_BASE_ADDRESS_SPACE_MEMORY,
-                     &proxy->bar);
 
     if (!kvm_has_many_ioeventfds()) {
         proxy->flags &= ~VIRTIO_PCI_FLAG_USE_IOEVENTFD;