Merge "Make kernel prebuilts writable after copying them." am: b327befa

Original change: https://android-review.googlesource.com/c/platform/build/+/2506189



Change-Id: I5324afbb42bacfd419026a4915c9ab3e330c660f
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>