Merge remote-tracking branch 'remotes/cohuck/tags/s390x-20170815' into staging

Merge remote-tracking branch 'remotes/cohuck/tags/s390x-20170815' into staging

Regression fix for 'make clean' on s390x.

# gpg: Signature made Tue 15 Aug 2017 08:24:54 BST
# gpg:                using RSA key 0xDECF6B93C6F02FAF
# 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-20170815:
  pc-bios/s390-ccw: Use rm command during make clean

Signed-off-by: Peter Maydell <[email protected]>