Merge remote-tracking branch 'remotes/cohuck/tags/s390x-20170421' into staging

The first batch of s390x changes for 2.10:
- the new compat machine
- several cleanups and optimizations
- introspection for css ids

# gpg: Signature made Fri 21 Apr 2017 08:36:25 BST
# gpg:                using RSA key 0xDECF6B93C6F02FAF
# gpg: Good signature from "Cornelia Huck <huckc@linux.vnet.ibm.com>"
# gpg:                 aka "Cornelia Huck <cornelia.huck@de.ibm.com>"
# Primary key fingerprint: C3D0 D66D C362 4FF6 A8C0  18CE DECF 6B93 C6F0 2FAF

* remotes/cohuck/tags/s390x-20170421:
  s390x: Drop useless casts
  s390x: register I/O adapters per ISC during init
  s390x/flic: cache flic in s390_get_flic
  s390x: initialize flic before I/O subsystems
  s390x: use enum for adapter type and standardize its naming
  s390x/css: consolidate the devno property for ccw devices
  s390x/css: provide introspection for virtual subchannel and device busid
  s390x/css: introduce read-only property type for device ids
  s390x/pci: make printf always compile in debug output
  s390x/kvm: make printf always compile in debug output
  s390x: introduce 2.10 compat machine

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