[autotest] Rename build target from beaglebone to beaglebone_servo

Related CL:
https://chromium-review.googlesource.com/#/c/180682/

BUG=None
TEST=manual test against local devserver
CQ-DEPEND=CL:181875

Change-Id: Id909497ce30ac57e34ec4bf0187eb2abf9e7b4ac
Reviewed-on: https://chromium-review.googlesource.com/181814
Reviewed-by: Dan Shi <dshi@chromium.org>
Tested-by: Dan Shi <dshi@chromium.org>
Commit-Queue: Dan Shi <dshi@chromium.org>
2 files changed