Merge remote-tracking branch 'remotes/dgibson/tags/ppc-for-2.6-20160229' into staging

ppc patch queue for 2016-02-29

Some more accumulated patches for target-ppc, pseries machine type and
related devices to fit in before the qemu-2.6 soft freeze.
    * Mostly bugfixes and small cleanups for spapr and Mac platforms

# gpg: Signature made Mon 29 Feb 2016 06:56:34 GMT 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-2.6-20160229:
  xics: report errors with the QEMU Error API
  migration: allow machine to enforce configuration section migration
  spapr: skip configuration section during migration of older machines
  dbdma: warn when using unassigned channel
  spapr: disable vmdesc submission for old machines
  spapr_pci: fix irq leak in RTAS ibm,change-msi
  spapr_pci: kill useless variable in rtas_ibm_change_msi()
  spapr_rng: disable hotpluggability

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