Update kernel to builds 8721220 am: 28fa3c89cc am: 78041742e4

Original change: https://android-review.googlesource.com/c/kernel/prebuilts/common-modules/virtual-device/5.15/x86-64/+/2125081

Change-Id: I57c4a529c733ea32af5d5c5ddf2de7d4b9998b91
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>