Allow data/ in root for EdgeOS

BUG=b/287334438
TEST=built the image with /data/ and saw that it wasn't rejected
RELEASE_NOTE=None

Change-Id: Ibc058fc0d31d1c736fd365b8f81106c2817ef79c
Reviewed-on: https://cos-review.googlesource.com/c/third_party/platform/crosutils/+/64570
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-by: Robert Kolchmeyer <rkolchmeyer@google.com>
Reviewed-by: Alan Berryhill <berryhill@google.com>