tpm_tis: Only probe iTPMs

Detect iTPMs through the vendor ID on the hardware interface and only
probe the device if the manufacturer is found to be Intel. This
obsoletes a previously added delay necessary for some TPMs but not iTPMs.

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Signed-off-by: Rajiv Andrade <srajiv@linux.vnet.ibm.com>