Update kernel to builds 8749440 am: efa6b68273 am: 6b85e6cfdd am: 3b7e9ba9ac

Original change: https://android-review.googlesource.com/c/kernel/prebuilts/5.4/arm64/+/2133094

Change-Id: I1c9540743dce54d5a0137b45124e482c432c047b
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>