virtio, pc: fixes, features

virtio support for region caches broke a bunch of stuff - fixing most of
it though it's not ideal.  Still pondering the right way to fix it.
New: VM gen ID and hotplug for PXB.

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

# gpg: Signature made Thu 02 Mar 2017 06:19:17 GMT
# gpg:                using RSA key 0x281F0DB8D28D5469
# gpg: Good signature from "Michael S. Tsirkin <mst@kernel.org>"
# gpg:                 aka "Michael S. Tsirkin <mst@redhat.com>"
# Primary key fingerprint: 0270 606B 6F3C DF3D 0B17  0970 C350 3912 AFBE 8E67
#      Subkey fingerprint: 5D09 FD08 71C8 F85B 94CA  8A0D 281F 0DB8 D28D 5469

* remotes/mst/tags/for_upstream:
  hw/pxb-pcie: fix PCI Express hotplug support
  tests/acpi: update DSDT after last patch
  acpi: simplify _OSC
  virtio: unbreak virtio-pci with IOMMU after caching ring translations
  virtio: add missing region cache init in virtio_load()
  virtio: invalidate memory in vring_set_avail_event()
  virtio: guard vring access when setting notification
  virtio: check for vring setup in virtio_queue_empty
  MAINTAINERS: Add VM Generation ID entries
  tests: Move reusable ACPI code into a utility file
  qmp/hmp: add query-vm-generation-id and 'info vm-generation-id' commands
  ACPI: Add Virtual Machine Generation ID support
  ACPI: Add vmgenid blob storage to the build tables
  docs: VM Generation ID device description
  linker-loader: Add new 'write pointer' command

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>