Move probe() from hwid_tool into gooftool.

Since probe only makes sense on a DUT, and since probing requires
modules only available on DUTs, the probe command does not belong
in hwid_tool.

As part of the move, clean up the code a bit.

The output of probe should be tolerably human-readable, but
primarily machine parseable.  This CL cleans things up to only
use yaml-encoded output.

Probe result cooking is cleaned up as well.

BUG=chrome-os-partner:8616
TEST=run gooftool --probe and --verify-hwid

Change-Id: I1fe9382cbb25dd94b2d8a31f66158ed03f773255
Reviewed-on: https://gerrit.chromium.org/gerrit/18950
Commit-Ready: Tammo Spalink <tammo@chromium.org>
Reviewed-by: Tammo Spalink <tammo@chromium.org>
Tested-by: Tammo Spalink <tammo@chromium.org>
5 files changed