faft: Chrome EC class supports a reboot method

So far, we do a EC reboot by either sending a EC command or using client
side ectool. This CL make Chrome EC class provide a single interface
to require EC reboot. Several reboot types are supported:
     default: EC soft reboot;
     'hard': EC hard/cold reboot;
     'ap-off': Leave AP off after EC reboot (by default, EC turns
               AP on after reboot if lid is open).

BUG=chromium-os:35254
TEST=run_remote_tests.sh --board link --remote dut FAFTSetup

Change-Id: Iabbd87ee7f06b8ef361bd56016fadc9696517cec
Reviewed-on: https://gerrit.chromium.org/gerrit/36862
Reviewed-by: Vic Yang <victoryang@chromium.org>
Commit-Ready: Tom Wai-Hong Tam <waihong@chromium.org>
Tested-by: Tom Wai-Hong Tam <waihong@chromium.org>
3 files changed