Merge remote-tracking branch 'remotes/cohuck/tags/s390x-20160324' into staging

Support for booting from virtio-scsi devices in the s390-ccw bios.

# gpg: Signature made Thu 24 Mar 2016 08:14:21 GMT 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-20160324:
  s390-ccw.img: rebuild image
  pc-bios/s390-ccw: disambiguation of "No zIPL magic" message
  pc-bios/s390-ccw: enhance bootmap detection
  pc-bios/s390-ccw: enable virtio-scsi
  pc-bios/s390-ccw: add virtio-scsi implementation
  pc-bios/s390-ccw: add scsi definitions
  pc-bios/s390-ccw: add simplified virtio call
  pc-bios/s390-ccw: make provisions for different backends
  pc-bios/s390-ccw: add vdev object to store all device details
  pc-bios/s390-ccw: update virtio implementation to allow up to 3 vrings
  pc-bios/s390-ccw: qemuize types
  pc-bios/s390-ccw: add utility functions and "export" some others
  pc-bios/s390-ccw: virtio_panic -> panic
  pc-bios/s390-ccw: add more disk layout checks

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