futility: cmd_update: Add more legacy updater options
futility: cmd_update: Add more legacy updater options

To make it easier for integration with legacy firmware updater, we want
to add few options:

 -m, --mode MODE
 -d, --debug
 -v, --verbose

BUG=chromium:875551
TEST=make futil; tests/futility/run_test_scripts.sh $(pwd)/build/futility
BRANCH=None

Change-Id: I6f045db0a8e9b5c73c1f0be2b52a71a7ee2a495e
Signed-off-by: Hung-Te Lin <8a7fce4940baad93a69f5073b383c85deed9d9c4@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1193043
Reviewed-by: Randall Spangler <62698fdbb84d1779579ee80c3f39fac22017e5bc@chromium.org>

coreboot/vboot,coreboot/vboot,coreboot/vboot,coreboot/vboot,coreboot/vboot