am a6589d78: (-s ours) am 7750d90d: (-s ours) hammerhead: update prebuilt kernel

* commit 'a6589d787b7bfd97fb6384dd0c706deac06218f8':
tree: b74aa191ac219c45a56f93a9e56a4d76bd396e4f
  1. zImage-dtb