Add option to use mocked TPM driver

firmware/lib/mocked_tpm_bootmode.c

Index: firmware/lib/mocked_tpm_bootmode.c
diff --git a/firmware/lib/mocked_tpm_bootmode.c b/firmware/lib/mocked_tpm_bootmode.c
new file mode 100644
index 0000000000000000000000000000000000000000..980c3a50352fe670d9a7f5371204bf6323b2bc6a
--- /dev/null
+++ b/firmware/lib/mocked_tpm_bootmode.c
@@ -0,0 +1,16 @@
+/* Copyright (c) 2011 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.
+ *
+ * Functions for updating the TPM state with the status of boot path.
+ */
+
+#include "tpm_bootmode.h"
+
+#include "tss_constants.h"
+
+
+uint32_t SetTPMBootModeState(int developer_mode, int recovery_mode,
+                             int fw_keyblock_flags) {
+  return TPM_SUCCESS;
+}