Merge remote-tracking branch 'remotes/cohuck/tags/s390x-20180712' into staging

Merge remote-tracking branch 'remotes/cohuck/tags/s390x-20180712' into staging

- fix confusion around sizes in storage attribute migration
- remove NULL check on error_propagate() in virtio-ccw

# gpg: Signature made Thu 12 Jul 2018 10:27:28 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-20180712:
  error: Remove NULL checks on error_propagate() calls
  s390x/storage attributes: fix CMMA_BLOCK_SIZE usage

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