Merge remote-tracking branch 'remotes/dgibson/tags/ppc-for-2.6-20160418' into staging

ppc patch queue for 2-16-04-18

Three bugfixe patches for 2.6 here.
* Two for bad implementation of some of the strong load/store
  instructions

* One for bad migration of the XER register.  This is a regression
  from 2.5, cause by a change in the way we represent at XER during
  runtime.

# gpg: Signature made Mon 18 Apr 2016 06:17:03 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-2.6-20160418:
  ppc: Fix migration of the XER register
  ppc: Fix the bad exception NIP value and the range check in LSWX
  ppc: Fix the range check in the LSWI instruction

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