FAFT: ADB gets the root access at the first call

Some commands FAFT calls requires the root access. Grant it at
the first call.

BUG=chromium:516398,chromium:527484
TEST=Ran a FAFT test on Ryu.

Change-Id: I4bfee45775737f1cc1b9918539349dee873e4f66
Reviewed-on: https://chromium-review.googlesource.com/295895
Commit-Ready: Wai-Hong Tam <waihong@chromium.org>
Tested-by: Wai-Hong Tam <waihong@chromium.org>
Reviewed-by: danny chan <dchan@chromium.org>
1 file changed