attestation: create template for TPM2.0 support implementation

Finish abstracting the interface to TPM.
Create empty template for TPM2.0 support implementation.
Fix build to depend on trousers/trunks for tpm/tpm2 respectively.

TEST=Boot on kevin with USE="-tpm tpm2", check that attestationd starts

Change-Id: I6ee6f37fe1d2727d3fd1706de76b325c8b2f0c3d
Commit-Ready: Andrey Pronin <>
Tested-by: Andrey Pronin <>
Reviewed-by: Darren Krahn <>
11 files changed