Following the recent extension of QEMU with a TPM emulator device,
update the specs describing for how to interact with the device.

The results of commands run inside a Linux VM are expected to be
similar to those when the TPM passthrough device is used, so we
just reuse that.

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>