common: add location to ArtifactsByService.Firmware

BUG=chromium:1034529
TEST=generate

Change-Id: I780ce2d20fd611b9cedcd4ea92c375de7ecc3587
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/infra/proto/+/2659914
Reviewed-by: Alex Klein <saklein@chromium.org>
Commit-Queue: LaMont Jones <lamontjones@chromium.org>
2 files changed