Use enforceCallingOrSelfPermission for ContextHub APIs

Previously, checkCallingPermission was used which fails when an IPC
isn't used (e.g. something in the system server calls our APIs).
Additionally, enforceCallingOrSelfPermission helps throw an exception
with better logging than the check and throw does today.

Fixes: 220167285
Test: Call from system server code
Change-Id: I152ff750fa1505628bfe7f9cd78f21a222eefa87