automated: workload-automation: allow for custom output path

In order to make result postprocessing possible in the LAVA job, WA
results can now be saved in the custom path that can be set as parameter

Change-Id: If9faac3d20fa10297ed8dc65aa5b2f3a0dae0ea4
Signed-off-by: Milosz Wasilewski <milosz.wasilewski@linaro.org>
4 files changed