futility: updater: Skip applying white label for local build
futility: updater: Skip applying white label for local build

For developers running a local build on white label models, currently
the chromeos-firmwareupdate will always fail if VPD `whitelabel_tag` is
set because the `keyset/` folder does not exist (which was created by
signer bot).

Developers in this case usually don't really care about which key to use
and will be happy with the default (DEV signed) keys, also the key
compatibility will be still checked later, so we can skip the white
label patching if no keyset folder, which would allow developers getting
same experience on WL and non-WL devices.

BUG=b:120268135
TEST=TEST=make futil; tests/futility/run_test_scripts.sh $(pwd)/build/futility
BRANCH=None

Change-Id: I3992301ff4c406096e11e1ae8129f2f68b2319b5
Signed-off-by: Hung-Te Lin <8a7fce4940baad93a69f5073b383c85deed9d9c4@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1356688
Reviewed-by: C Shapiro <97eabdef1f1c3aaebe144a81b3e6d8d879701c39@chromium.org>

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