project-lakitu: fix boot on ARM64

Use correct function name, get_layout_partition_number,
which was changed to get_layout_part_number by a last-minute
search/replace operation.

Also add an error detection logic for this condition instead
of failing silently later on and generating corrupted image.

BUG=b/179918454
TEST=presubmit
RELEASE_NOTE=None

Change-Id: I9e549914a7fec51b1db877f7a3ac18cbb44bdf98
Reviewed-on: https://cos-review.googlesource.com/c/cos/overlays/board-overlays/+/13470
Reviewed-by: Roy Yang <royyang@google.com>
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
1 file changed