Complete OemLockService API.

The API was missing a call to query the name of the HAL which is used to
identify the security protocol in use. The API also didn't conform to
the documentation in a few cases.

Bug: 120078865
Test: gts-tradefed run gts -m GtsOemLockServiceTestCases
Change-Id: Ib1ec06f99bbe21710d4d8f61252d6431ffab51a6