firmware_builder: Make cros lint happy
firmware_builder: Make cros lint happy

BRANCH=none
BUG=none
TEST=cros lint ./firmware_builder.py
TEST=./firmware_builder.py --help
TEST=./firmware_builder.py --metrics $(mktemp /tmp/fwbld.XXX) test
TEST=./firmware_builder.py --metrics $(mktemp /tmp/fwbld.XXX) build

Signed-off-by: Craig Hesling <383db090fd8ef907a606ac8a9eccd2962bc489cf@chromium.org>
Change-Id: I0c2b03d3197fc021e93ce8a0029cdd465b9eb457
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3082336
Reviewed-by: Paul Fagerburg <d8c44b60afb21c60f56d931aa690ca1cf34910c8@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec