Updater: Change platform check to base on firmware ID.

The "platform name" check was made long time ago when we need to run
factory installation on systems using Non-Chrome firmware (ex, legacy UEFI).

Now every boards use Chrome firmware from the very beginning and no Non-Chrome
firmware is pre-flashed for manufacturing, so it should be safe to replace the
mosys-based platform check by simply firmware ID.

This also helps to prevent:
 1. Board release process blocked due to mosys support.
 2. Need to match mosys "platform name" output to updater ebuilds.

BUG=chromium:431442
TEST=emerge-link chromeos-firmware-link;
     grep TARGET_PLATFORM /build/link/usr/sbin/chromeos-firmwareupdate
     # see Google_Link, the correct name.
     (on Link) # chromeos-firmwareupdate --mode=autoupdate # success.

Change-Id: Idc64e8a260e61d92d308023b289346234bbe9b36
Reviewed-on: https://chromium-review.googlesource.com/228752
Reviewed-by: David Hendricks <dhendrix@chromium.org>
Commit-Queue: Hung-Te Lin <hungte@chromium.org>
Tested-by: Hung-Te Lin <hungte@chromium.org>
6 files changed