autotest: Support the flow to update RW firmware for BIOS and EC

This change completes the flow to update RW firmware, through
CrosHost.firmware_install(), Servo.program_bios()/Servo.program_ec(),
ProgrammerV3RwOnly.program_bios(), to FlashromProgrammer.program().

BUG=chromium:555709
TEST=Ran the following script:
import common
from autotest_lib.server import hosts
h = hosts.create_host(DUT_IP, servo_args={})
h.firmware_install(RO_VERSION)
h.firmware_install(RW_VERSION, rw_only=True)

Checked the DUT installed the proper RO and RW firmware (BIOS and EC).

Change-Id: I5dfca7b3d80c6cd23b0c1e3d2605fce008bd60b2
Reviewed-on: https://chromium-review.googlesource.com/320825
Commit-Ready: Wai-Hong Tam <waihong@chromium.org>
Tested-by: Wai-Hong Tam <waihong@chromium.org>
Reviewed-by: Dan Shi <dshi@google.com>
3 files changed