tss: add tpm2_Certify, tpm2_ActivateCredential and tpm2_PolicyOR

tpm2_Certify is used to verify that a given object is resident in the
TPM.  tpm2_ActivateCredential is used to decrypt a challenge from a
privacyCA and constructing the high template for the EK to use with
this requires PolicyOR.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>