Add servo_serial property in servo module.

Also propagate servo serial number to flashrom programmer.

BUG=none
TEST=manually tested on my DUT

Change-Id: I1106221913ffd7adeb8d1f4118699ecc18bcf4ef
Reviewed-on: https://chromium-review.googlesource.com/196419
Reviewed-by: Vic Yang <victoryang@chromium.org>
Commit-Queue: Ricky Liang <jcliang@chromium.org>
Tested-by: Ricky Liang <jcliang@chromium.org>
2 files changed