tpm: add support for TPMv2.x I2C chips

Add the tpm2_tis_i2c driver that should support any TPMv2 compliant
I2C chips, such as the NPCT75X chip.

[Ilias rename priv_auto_alloc_size to priv_auto]
Signed-off-by: Eddie James <eajames@linux.ibm.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>