pc,pci,virtio: bugfixes, improvements

vhost-user-rng support.
Fixes all over the place.

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

# gpg: Signature made Wed 07 Jul 2021 14:29:30 BST
# 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]
# 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:
  MAINTAINERS: Add maintainer for vhost-user RNG implementation
  docs: add slot when adding new PCIe root port
  acpi/ged: fix reset cause
  tests: acpi: pc: update expected DSDT blobs
  acpi: pc: revert back to v5.2 PCI slot enumeration
  tests: acpi: prepare for changing DSDT tables
  migration: failover: reset partially_hotplugged
  virtio-pci: Changed return values for "notify", "device" and "isr" read.
  virtio-pci: Added check for virtio device in PCI config cbs.
  virtio-pci: Added check for virtio device presence in mm callbacks.
  hw/pci-host/q35: Ignore write of reserved PCIEXBAR LENGTH field
  virtio: Clarify MR transaction optimization
  virtio: disable ioeventfd for record/replay

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