Merge remote-tracking branch 'remotes/cohuck/tags/s390x-20150903' into staging

First batch of s390x patches for 2.5:
- introduce 2.5 compat machine
- support for migration of storage keys

# gpg: Signature made Thu 03 Sep 2015 11:28:06 BST using RSA key ID C6F02FAF
# gpg: Good signature from "Cornelia Huck <huckc@linux.vnet.ibm.com>"
# gpg:                 aka "Cornelia Huck <cornelia.huck@de.ibm.com>"

* remotes/cohuck/tags/s390x-20150903:
  s390x: Disable storage key migration on old machine type
  s390x: Migrate guest storage keys (initial memory only)
  s390x: Info skeys sub-command
  s390x: Dump-skeys hmp support
  s390x: Dump storage keys qmp command
  s390x: Enable new s390-storage-keys device
  s390x: Create QOM device for s390 storage keys
  s390x: add 2.5 compat s390-ccw-virtio machine

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

diff --cc MAINTAINERS
Simple merge