KEYS: trusted: Move TPM2 trusted keys code

Move TPM2 trusted keys code to trusted keys subsystem. The reason
being it's better to consolidate all the trusted keys code to a single
location so that it can be maintained sanely.

Also, utilize existing tpm_send() exported API which wraps the internal
tpm_transmit_cmd() API.

Suggested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>