setup_board: --brick overrides --board.

This is necessary because --board has a default value, which may be
non-empty. Same logic was applied in (e.g.) cros_workon.

BUG=None
TEST=./setup_board --brick overrides --board value and emits a warning.

Change-Id: I485ad55f46764904851c7c3382257765d37ca6cb
Reviewed-on: https://chromium-review.googlesource.com/262044
Tested-by: Gilad Arnold <garnold@chromium.org>
Reviewed-by: Bertrand Simonnet <bsimonnet@chromium.org>
Commit-Queue: Gilad Arnold <garnold@chromium.org>
1 file changed