Keystore 2.0 SPI: Fix various CTS failures.

* Add missing purpose to HMAC operations.
* Pass correct key descriptor to wrapped key import.
* Corrected error message on Import wrapped key failure due to missing
  wrapping key.
* Do not bail out on missing attestation challenge when device
  properties are requested.
* Fix AndroidKeyStoreKey.equals(). It is sufficient to compare the
  unique key ID.

Test: Keystore CTS tests.
Change-Id: Id3b93b18486e3a818ae8e91be6344294ec592e68