bootanalyze: add optinal serial argument to support testing more than one devices

Bug: 33210752
Test: python packages/services/Car/tools/bootanalyze/bootanalyze.py -r -c packages/services/Car/tools/bootanalyze/config.yaml -n 10 -p 5VT7N15817000492

Change-Id: Ib755de08e322ef08e352e695596ea79dd140bd3c
1 file changed