sys logs info: call touchpad activity script to get log data

Rather than make this one-line command more complext, move it into a
helper script.

BUG=chromium-os:25678
TEST=tested on device

Change-Id: If6abb50bf0c4a15776388d2c7c112c1fd30f37f3
Reviewed-on: https://gerrit.chromium.org/gerrit/15070
Commit-Ready: Andrew de los Reyes <adlr@chromium.org>
Reviewed-by: Andrew de los Reyes <adlr@chromium.org>
Tested-by: Andrew de los Reyes <adlr@chromium.org>