hikey960: set default kernel to 5.10 am: 7788ffd9eb

Original change: https://android-review.googlesource.com/c/device/linaro/hikey/+/2469591

Change-Id: I56e6afbcdeede61072569dc08eaa6750ecd4c992
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>