Merge remote-tracking branch 'remotes/dgibson/tags/ppc-for-2.6-20160426' into staging

ppc patch queue for 2016-04-26 (last minute qemu-2.6 fix)

This just has one, last-minute, fix for a serious regression of memory
hotplug.

Patch author's comment:
    Really sorry for the way last-minute fix, but without this memory
    hotplug is totally broken :( Hoping to get this in for Wednesday's
    RC4, which I think will be the final before release.

# gpg: Signature made Tue 26 Apr 2016 03:52:20 BST using RSA key ID 20D9B392
# gpg: Good signature from "David Gibson <david@gibson.dropbear.id.au>"
# gpg:                 aka "David Gibson (Red Hat) <dgibson@redhat.com>"
# gpg:                 aka "David Gibson (ozlabs.org) <dgibson@ozlabs.org>"
# gpg: WARNING: This key is not certified with sufficiently trusted signatures!
# gpg:          It is not certain that the signature belongs to the owner.
# Primary key fingerprint: 75F4 6586 AE61 A66C C44E  87DC 6C38 CACA 20D9 B392

* remotes/dgibson/tags/ppc-for-2.6-20160426:
  spapr_drc: fix aborts during DRC-count based hotplug

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