Break out header file to allow embedding of the the TTC.

Signed-off-by: Edgar E. Iglesias <edgar.iglesias@amd.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Luc Michel <luc@lmichel.fr>
Reviewed-by: Francisco Iglesias <frasse.iglesias@gmail.com>
Message-id: 20220331222017.2914409-2-edgar.iglesias@gmail.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>