autotest: Update DUT proper fw RO/RW labels after a firmware update

The labels of fw version have to be updated. If only updating RW,
clear and add a fwrw_version label. If updating both RO and RW, clear
and add both fwro_version and fwrw_version labels.

BUG=chromium:555709
TEST=Ran the following tests and checked the labels:
test_that --board $BOARD --args "value=$RO_BUILD" DUT_IP provision_FirmwareUpdate
test_that --board $BOARD --args "value=$RW_BUILD" DUT_IP provision_FirmwareUpdate.rw_only

Change-Id: Ibc705ec1c0c70403993ab7aebc8e2ce729b24483
Reviewed-on: https://chromium-review.googlesource.com/320605
Commit-Ready: Wai-Hong Tam <waihong@chromium.org>
Tested-by: Wai-Hong Tam <waihong@chromium.org>
Reviewed-by: Dan Shi <dshi@google.com>
2 files changed