Merge remote-tracking branch 'remotes/cohuck/tags/s390x-20150430' into staging

First pile of s390x patches for 2.4, including:
- some cleanup patches
- sort most of the s390x devices into categories
- support for the new STSI post handler, used to insert vm name and
  friends
- support for the new MEM_OP ioctl (including access register mode)
  for accessing guest memory

# gpg: Signature made Thu Apr 30 12:56:58 2015 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-20150430:
  kvm: better advice for failed s390x startup
  s390x/kvm: Support access register mode for KVM_S390_MEM_OP ioctl
  s390x/mmu: Use ioctl for reading and writing from/to guest memory
  s390x/kvm: Put vm name, extended name and UUID into STSI322 SYSIB
  linux-headers: update
  s390x/mmu: Use access type definitions instead of magic values
  s390x/ipl: sort into categories
  sclp: sort into categories
  s390-virtio: sort into categories
  virtio-ccw: sort into categories

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