Log VINTF manifest success/failure cases.

These logs are critical to understand the operation of the system, and
do not spam (1/hal start or 1/hal request). Most importantly, if a
manifest fails to be read for whatever reason, this is logged (null
manifest case).

Bug: 151696835
Test: boot, and verify logs of successful hal retrivals
Test: boot, and verify logs w/ patch which causes VINTF to fail the
  first time, and verify that this causes a single crash which gives us
  the ability to still find and detect a critical error, but allows the
  system functionality to continue to work.
Change-Id: I0a26b875947878656d6eda03ffebce97ebb6139e
Merged-In: I0a26b875947878656d6eda03ffebce97ebb6139e