selftests: tpm: upgrade TPM2 tests from Python 2 to Python 3

Python 2 is no longer supported by the Python upstream project, so
upgrade TPM2 tests to Python 3.

Fixed minor merge conflicts
Shuah Khan <skhan@linuxfoundation.org>

Signed-off-by: Pengfei Xu <pengfei.xu@intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>