arm_trusted_firmware_uprev: move to contrib

This code isn't supported by the build team, so move it to contrib/.

BUG=None
TEST=None

Change-Id: I32abfd56a16102f7549437645dd3f462128ac1f8
Reviewed-on: https://chromium-review.googlesource.com/1178331
Commit-Ready: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>