Fixes and cleanups for the 2.12 softfreeze.

# gpg: Signature made Thu 08 Mar 2018 17:53:14 GMT
# 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-20180308:
  s390x/virtio: Convert virtio-ccw from *_exit to *_unrealize
  pc-bios/s390-ccw: Move string arrays from bootmap header to .c file
  s390x/sclp: clean up sclp masks
  s390x/sclp: proper support of larger send and receive masks
  vfio-ccw: license text should indicate GPL v2 or later
  s390x/sclpconsole: Remove dead code - remove exit handlers
  numa: we don't implement NUMA for s390x
  hw/s390x: Add the possibility to specify the netboot image on the command line
  target/s390x: Remove leading underscores from #defines
  s390/ipl: only print boot menu error if -boot menu=on was specified
  hw/s390x/ipl: Bail out if the network bootloader can not be found

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