pc,pci,virtio: features, fixes

virtio-iommu support for x86/ACPI.
Fixes, cleanups all over the place.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

# gpg: Signature made Mon 01 Nov 2021 07:36:22 PM EDT
# gpg:                using RSA key 5D09FD0871C8F85B94CA8A0D281F0DB8D28D5469
# gpg:                issuer "mst@redhat.com"
# gpg: Good signature from "Michael S. Tsirkin <mst@kernel.org>" [full]
# gpg:                 aka "Michael S. Tsirkin <mst@redhat.com>" [full]

* remotes/mst/tags/for_upstream:
  hw/i386: fix vmmouse registration
  pci: Export pci_for_each_device_under_bus*()
  pci: Define pci_bus_dev_fn/pci_bus_fn/pci_bus_ret_fn
  hw/i386/pc: Allow instantiating a virtio-iommu device
  hw/i386/pc: Move IOMMU singleton into PCMachineState
  hw/i386/pc: Remove x86_iommu_get_type()
  hw/acpi: Add VIOT table
  vhost-vdpa: Set discarding of RAM broken when initializing the backend
  qtest: fix 'expression is always false' build failure in qtest_has_accel()

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>