Restore verity state when verified partition is reflashed

Store verity state separately for each verified partition, and store
a hash of the last verity table signature for each partition. If the
signature changes, assume the partition has been reflashed and reset
verity state.

Bug: 20006638
Change-Id: I1c85fb816bfec1a54b1033c938bf1fdaf572f849
1 file changed