Refactor bufferhub token to be more secure

Now BufferHubService will use HMAC hashing from openssl library to
enhance the security of the token.

The token handle will use its first int to store token id, then the HMAC
hash of the token id, so that BufferHubService could store token in
mTokenMap using token id as the key to improve looking up performance.

Test: VtsHalBufferHubV1_0TargetTest
Change-Id: Ica9639bc1504a477c6a1b1f703399bb07b3a2d2c
Fix: 118180214