Update kernel to builds 6481591 am: d81e1d9139 am: 38b5175c25

Change-Id: Ib3a1dbc9af0460aa04879de99edbf138668c8b1f
tree: d4739c85ac4a999663b2aaaa86ea198e19b76785
  1. 5.4-arm64/
  2. 5.4-x86_64/
  3. scripts/
  4. Android.bp
  5. METADATA
  6. OWNERS
  7. TEST_MAPPING