Merge remote-tracking branch 'remotes/stefanberger/tags/pull-tpm-2017-11-15-1' into staging

Merge tpm 2017/11/15 v1

# gpg: Signature made Wed 15 Nov 2017 11:51:47 GMT
# gpg:                using RSA key 0x75AD65802A0B4211
# gpg: Good signature from "Stefan Berger <stefanb@linux.vnet.ibm.com>"
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg:          There is no indication that the signature belongs to the owner.
# Primary key fingerprint: B818 B9CA DF90 89C2 D5CE  C66B 75AD 6580 2A0B 4211

* remotes/stefanberger/tags/pull-tpm-2017-11-15-1:
  tpm_tis: Return 0 for every register in case of failure mode
  tpm_tis: Return TPM_VERSION_UNSPEC in case of BE failure
  tpm-emulator: protect concurrent ctrl_chr access
  specs: Extend TPM spec with TPM emulator description

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