This driver adds support for Infineon's new SLB 9645 TT 1.2 I2C TPMs,
which supports clockstretching, combined reads and a bus speed of
up to 400khz. The device also has a new device id.

The driver works now also fine with device trees, so you can
instantiate your device by adding:
 +       tpm {
 +               compatible = "infineon,slb9645tt";
 +               reg = <0x20>;
 +       };
 for SLB 9645 devices or

 +       tpm {
 +               compatible = "infineon,slb9635tt";
 +               reg = <0x20>;
 +       };
 for SLB 9635 devices

to your device tree.
tpm_i2c_infineon is also retained as a compatible id as a fallback to
slb9635 protocol.

The driver was tested on Beaglebone.
Signed-off-by: Peter Huewe <peter.huewe@infineon.com>
Signed-off-by: Kent Yoder <key@linux.vnet.ibm.com>