fix: update kernel model runtime packaging

[daiyongyuan]

Summary

• update the bbkernel submodule for chip-aware ModelTest runtime packaging
• prevent LeNet kernel images from reusing stale chip-less workload outputs
• include the aligned Stable Diffusion model naming fix

Dependency

• fix: align P2E boot and model runtime layout bbkernel#1

Merge the bbkernel PR first so the referenced submodule commit is available from its main branch.

Verification

• rebuilt fw_payload-lenet.hex successfully
• verified the initramfs contains LeNet parameters and images
• P2E LeNet passed with classification 8 and return code 0

[shirohasuki]

LGTM