Update kernel to builds 6638796 am: f0c9d0b1fe am: 045b001fd6

Original change: https://googleplex-android-review.googlesource.com/c/device/google/cuttlefish_kernel/+/11995650

Change-Id: If4c90e0f6d87268dd3190477e9760c47d543c371
tree: 2a9396841feb7a2d73e69e32bb65c0694cda1dee
  1. 5.4-arm64/
  2. 5.4-x86_64/
  3. scripts/
  4. Android.bp
  5. OWNERS
  6. TEST_MAPPING