keystore-engine: Couple of bug fixes for HIDL keystore

Fixes for issues found in wifi integration tests:
1. ensure_keystore_engine() needs to be invoked before we access
|g_keystore_backend|.
2. The HIDL backends need to return 0 when the operation succeeds.

Bug: 34603782
Test: Manual tests.
Change-Id: If61d3bef27dab6f4fb73113f0ed6d3e784a29f32
2 files changed
tree: d39913309c70c81955eb75ff4019f7c8c79d1c11
  1. keystore/
  2. keystore-engine/
  3. softkeymaster/
  4. MODULE_LICENSE_APACHE2
  5. NOTICE