libbinder_ndk: AIBinder_*_lt, clarify

For clarity (a reference to RefBase is omitted here since many of the
details in the platform documentation are irrelevant here, since they
are not exposed).

Bug: 177020658
Test: N/A
Change-Id: I5b33124422243c2eb2517bd5e5325010126a45f3
1 file changed