tpm_manager: Define the NVRAM API surface

This CL adds the NVRAM API to the TpmManager DBus interface.
This CL also implements the TpmManagerService to perform these
operations.

Bug: 24059570
TEST=FEATURES=test emerge-link tpm_manager

Change-Id: Ia9f26fde4c6acbd7bc568ddd5ac644b680c580b2
13 files changed