Add kernel_usb test suite

Boards on diff kernel version were separated from pool:stress not
to interfere with stress test suite.
Main kernel_usb test suite purpose is to catch USB detection
regressions.
Adding one test to run as part of the suite.

BUG=chromium:356880
TEST=Tested locally

Change-Id: I2ea0195503effd5a675f90690c088816c4b52369
Reviewed-on: https://chromium-review.googlesource.com/228892
Reviewed-by: Kris Rambish <krisr@chromium.org>
Tested-by: Kalin Stoyanov <kalin@chromium.org>
Commit-Queue: Kalin Stoyanov <kalin@chromium.org>
3 files changed