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>
diff --git a/drivers/tpm/Kconfig b/drivers/tpm/Kconfig
index eceff27..d59102d 100644
--- a/drivers/tpm/Kconfig
+++ b/drivers/tpm/Kconfig
@@ -185,6 +185,15 @@
 	  to the device using the standard TPM Interface Specification (TIS)
 	  protocol.
 
+config TPM2_TIS_I2C
+	bool "Enable support for TPMv2.x I2C chips"
+	depends on TPM_V2 && DM_I2C
+	help
+	  This driver supports TPMv2.x devices connected on the I2C bus.
+	  The usual TPM operations and the 'tpm' command can be used to talk
+	  to the device using the standard TPM Interface Specification (TIS)
+	  protocol.
+
 config TPM2_FTPM_TEE
 	bool "TEE based fTPM Interface"
 	depends on TEE && OPTEE && TPM_V2