Mosys fixes for Nautilus

This will make a mosys platform work for Nautilus unibuild firmware-updates
with non-unibuild firmware. If cros_config_read_sku_info fails, because
it doesn't have a sku_id, it will try again forcing the sku_id to be
zero.

BUG=b:112319097
TEST=local platform tests and tryjobs

Change-Id: I62e9140aa6d955e072be5c32d77c9f126576b2fe
Reviewed-on: https://chromium-review.googlesource.com/1176090
Commit-Ready: Gregory Meinke <gmeinke@chromium.org>
Tested-by: Gregory Meinke <gmeinke@chromium.org>
Reviewed-by: Jason Clinton <jclinton@chromium.org>
3 files changed