Merge remote-tracking branch 'remotes/dgibson/tags/ppc-for-2.9-20170329' into staging

ppc patch queue for 2017-03-29

Two more bugfixes of sufficient severity to warrant going into 2.9.

# gpg: Signature made Wed 29 Mar 2017 04:33:19 BST
# gpg:                using RSA key 0x6C38CACA20D9B392
# 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:                 aka "David Gibson (kernel.org) <dwg@kernel.org>"
# Primary key fingerprint: 75F4 6586 AE61 A66C C44E  87DC 6C38 CACA 20D9 B392

* remotes/dgibson/tags/ppc-for-2.9-20170329:
  spapr: fix memory hot-unplugging
  spapr: fix buffer-overflow

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