Fix default build arguments.

build_image: Only enable serial output on factory install and test images.

This is factory-branch-only change.
Enabling serial output on "all" images would cause signer test to fail.

BUG=chrome-os-partner:38520
TEST=./build_image test

Change-Id: I276aa23fc049141fb71084ab4722b4b5862656dc
Reviewed-on: https://chromium-review.googlesource.com/263031
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Commit-Queue: Hung-Te Lin <hungte@chromium.org>
Tested-by: Hung-Te Lin <hungte@chromium.org>
1 file changed