Add retry count and exception handling

Added retry count if lsusb cmd fails and exception handling.

TEST=Ran on lab machines
BUG=chromium:417585

Change-Id: Ifaad7ed5b3435d1c4c0adad24eafe8c38a98a7c1
Reviewed-on: https://chromium-review.googlesource.com/222027
Reviewed-by: Kalin Stoyanov <kalin@chromium.org>
Tested-by: jimish shah <jimishs@chromium.org>
Commit-Queue: jimish shah <jimishs@chromium.org>
Reviewed-by: jimish shah <jimishs@chromium.org>
1 file changed