locksettings: improve logging of LSKF verification

Improve the logging related to verifying the LSKF.

We generally don't want to be super verbose here, but it does make sense
to have an INFO message at the beginning and end.  There was already a
DEBUG message at the beginning and an INFO message near the end, but
they were unclear, so replace them with clearer INFO messages.

Bug: 268526331
Change-Id: Iaccbbd0d5a297bf97ff6ef31630eeec19fe3277b