Make TPM datagrams const, since they cannot be modified in the RO firmware.

firmware/lib/tpm_lite/include/tlcl.h

 /* Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 /* TPM Lightweight Command Library.
  *
  * A low-level library for interfacing to TPM hardware or an emulator.
  */
 
@@ skipping 11 matching lines @@
 
 /* Close and open the device.  This is needed for running more complex commands
  * at user level, such as TPM_TakeOwnership, since the TPM device can be opened
  * only by one process at a time.
  */
 void TlclCloseDevice(void);
 void TlclOpenDevice(void);
 
 /* Send data to the TPM and receive a response.  Returns 0 if success,
  * nonzero if error. */
-uint32_t TlclStubSendReceive(uint8_t* request, int request_length,
+uint32_t TlclStubSendReceive(const uint8_t* request, int request_length,
                              uint8_t* response, int max_length);
 
 /*****************************************************************************/
 /* Functions implemented in tlcl.c */
 
 /* Call this first.
  */
 void TlclLibInit(void);
 
 /* Logs to stdout.  Arguments like printf.
@@ skipping 108 matching lines @@
 
 /* Gets the entire set of permanent flags.
  */
 uint32_t TlclGetPermanentFlags(TPM_PERMANENT_FLAGS* pflags);
 
 /* Gets the entire set of volatile (ST_CLEAR) flags.
  */
 uint32_t TlclGetSTClearFlags(TPM_STCLEAR_FLAGS* pflags);
 
 #endif  /* TPM_LITE_TLCL_H_ */