tpm: Add HMAC session name/handle append

Add tpm2_append_name() for appending to the handle area of the TPM
command.  When TPM_BUS_SECURITY is enabled and HMAC sessions are in
use this adds the standard u32 handle to the buffer but additionally
records the name of the object which must be used as part of the HMAC
computation.  The name of certain object types (volatile and permanent
handles and NV indexes) is a hash of the public area of the object.
Since this hash is not known ahead of time, it must be requested from
the TPM using TPM2_ReadPublic() (which cannot be HMAC protected, but
if an interposer lies about it, the HMAC check will fail and the
problem will be detected).

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> # crypto API parts
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>