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 <[email protected]>"
# gpg:                 aka "Cornelia Huck <[email protected]>"
# gpg:                 aka "Cornelia Huck <[email protected]>"
# gpg:                 aka "Cornelia Huck <[email protected]>"
# gpg:                 aka "Cornelia Huck <[email protected]>"
# 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 <[email protected]>