Add init support for dm-verity logging mode

Add a built-in command for loading verity state. If dm-verity
will be started in logging mode, trigger verity-logging.

Needs changes from
  Ibb82953594d234f81ad21c40f524190b88e4ac8f

Change-Id: I5af4918f2f14fdd4d07f51c55837e08111fd3748