Force native byte order for timestamp HMAC

The previous C++ implementation for timestamp token generation fed in
the integer values in native (little) endian format, so override the
default impl here to do the same for compatibility with existing
consumers of timestamps.

Bug: 266879029
Test: atest CtsIdentityTestCases:android.security.identity.cts.UserAuthTest
Change-Id: I02d0dfafd6fe25f714ef14d2e6c2ed1ee33edc1e
1 file changed