project-lakitu: upgrade shim to vesion 15

Create ebuild for the latest shim release (15)

BUG=b/179529890
TEST=presubmit
RELEASE_NOTE=None

Change-Id: Ie9e885e227ec4834362de79b16335699953f41d9
Reviewed-on: https://cos-review.googlesource.com/c/cos/overlays/board-overlays/+/13950
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-by: Robert Kolchmeyer <rkolchmeyer@google.com>
Reviewed-by: Roy Yang <royyang@google.com>
6 files changed