Merge remote-tracking branch 'remotes/awilliam/tags/vfio-update-20180817.0' into staging

VFIO update 2018-08-17

 - Enhance balloon inhibitor for multiple users and use around vfio
   device assignment (Alex Williamson)

# gpg: Signature made Fri 17 Aug 2018 17:43:37 BST
# gpg:                using RSA key 239B9B6E3BB08B22
# gpg: Good signature from "Alex Williamson <alex.williamson@redhat.com>"
# gpg:                 aka "Alex Williamson <alex@shazbot.org>"
# gpg:                 aka "Alex Williamson <alwillia@redhat.com>"
# gpg:                 aka "Alex Williamson <alex.l.williamson@gmail.com>"
# Primary key fingerprint: 42F6 C04E 540B D1A9 9E7B  8A90 239B 9B6E 3BB0 8B22

* remotes/awilliam/tags/vfio-update-20180817.0:
  vfio/ccw/pci: Allow devices to opt-in for ballooning
  vfio: Inhibit ballooning based on group attachment to a container
  kvm: Use inhibit to prevent ballooning without synchronous mmu
  balloon: Allow multiple inhibit users

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