esys: Fix HMAC generation for policy sessions
esys: Fix HMAC generation for policy sessions

Policy sessions which do not include TPM2_PolicyAuthValue should not include
authValue in their HMAC computation.

Signed-off-by: Jeffrey Ferreira <3e1a4cb701ee13e77d374c5a95dfca99fcd463b8@gmail.com>

01org/tpm2-tss,tpm2-software/tpm2-tss,01org/TPM2.0-TSS,01org/TPM2.0-TSS,01org/TPM2.0-TSS,tpm2-software/tpm2-tss,01org/TPM2.0-TSS,tpm2-software/tpm2-tss,01org/tpm2-tss,01org/tpm2-tss