Avoid duplicated definition in llndk-versioning.h

Non-vendor modules may define llndk versioning macros manually. Avoid
redefining the macros if they are already defined outside of
llndk-versioning.h header.

Bug: 302113279
Test: m && m cts

Change-Id: Ibf984f2f2eed3594c824f2e97e17f2698e0515dd