bisect-kit: fix bug: servo_port is not a string

BUG=b:184105298
TEST=manually

Change-Id: Ie7f27c0eba5cba91c507ae0df39630f10b899d0a
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/bisect-kit/+/2833502
Tested-by: Zheng-Jie Chang <zjchang@chromium.org>
Auto-Submit: Zheng-Jie Chang <zjchang@chromium.org>
Reviewed-by: Kuang-che Wu <kcwu@chromium.org>
Commit-Queue: Kuang-che Wu <kcwu@chromium.org>
1 file changed