Update kernel to builds 7921849 am: acb0dc93db am: bda35e8e30 am: 1fa6d181bc

Original change: https://android-review.googlesource.com/c/kernel/prebuilts/5.10/arm64/+/1895255

Change-Id: Ia0103613648dfeddb1345528e36798a342a1cf4a