[TPM] Update the TPM drivers in the repository to a newer version

[TPM] Update the TPM drivers in the repository to a newer version
and also fixes the following:

- a problem introduced by a recent change to the xenbus_driver structure
requires driver-specific data to be stored in another data structures
- removes the #define'd MIN by min/min_t
- moves the sysfs entry to /sys/devices/xen/<vtpm-%d>
- fixes a bug occurring during cancellation of requests
- updates the default configuration to also compile the TPM V1.2 driver
submitted in part 2 of this patch
- all changes made to the generic TPM driver are surrounded by #ifdef
CONFIG_XEN's.

Signed-off-by: Stefan Berger <stefanb@us.ibm.com>