Merge remote-tracking branch 'remotes/cohuck/tags/s390x-20180820' into staging

Merge remote-tracking branch 'remotes/cohuck/tags/s390x-20180820' into staging

First round of s390x patches for 3.1:
- add compat machine for 3.1
- remove deprecated 's390-squash-mcss' option
- cpu models: add "max" cpu model, enhance feature group code
- kvm: add support for etoken facility and huge page backing

# gpg: Signature made Mon 20 Aug 2018 13:47:38 BST
# gpg:                using RSA key DECF6B93C6F02FAF
# gpg: Good signature from "Cornelia Huck <conny@cornelia-huck.de>"
# gpg:                 aka "Cornelia Huck <huckc@linux.vnet.ibm.com>"
# gpg:                 aka "Cornelia Huck <cornelia.huck@de.ibm.com>"
# gpg:                 aka "Cornelia Huck <cohuck@kernel.org>"
# gpg:                 aka "Cornelia Huck <cohuck@redhat.com>"
# Primary key fingerprint: C3D0 D66D C362 4FF6 A8C0  18CE DECF 6B93 C6F0 2FAF

* remotes/cohuck/tags/s390x-20180820:
  s390x: Enable KVM huge page backing support
  s390x/kvm: add etoken facility
  linux-headers: update
  s390x/cpumodel: Add "-cpu max" support
  s390x: remove 's390-squash-mcss' option
  s390x/cpumodel: enum type S390FeatGroup now gets generated
  s390x: introduce 3.1 compat machine

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