tpm: Reorganize the I2C TPM driver

This patch does a similar code reogranzation from
  http://patchwork.ozlabs.org/patch/132179/
which is based on an old version of code (fdt support and bus selection
still not in). It merges this tidy-up on top of the recent code. It does
not make any logical change.

tpm.c implements the interface defined in tpm.h based on underlying
LPC or I2C TPM driver. tpm.c and the underlying driver communicate
throught tpm_private.h.

Note: Merging the LPC driver with tpm.c is left to future patches.

Change-Id: Ie1384f5f9e3935d3bc9a44adf8de80c5a70a5f2b
Signed-off-by: Tom Wai-Hong Tam <waihong@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/README b/README
index b025dfc..3780564 100644
--- a/README
+++ b/README
@@ -1212,6 +1212,19 @@
 		CONFIG_TPM
 		Support TPM devices.
 
+		CONFIG_TPM_TIS_I2C
+		Support for i2c bus TPM devices. Only one device
+		per system is supported at this time.
+
+			CONFIG_TPM_TIS_I2C_BUS_NUMBER
+			Define the the i2c bus number for the TPM device
+
+			CONFIG_TPM_TIS_I2C_SLAVE_ADDRESS
+			Define the TPM's address on the i2c bus
+
+			CONFIG_TPM_TIS_I2C_BURST_LIMITATION
+			Define the burst count bytes upper limit
+
 		CONFIG_TPM_TIS_LPC
 		Support for generic parallel port TPM devices. Only one device
 		per system is supported at this time.