Quieten build issues with clang:

* typecast the enum to an int so clang doesn't produce a warning
  because the (current) enum max value is < than the array length.
  Sigh.

* Initialise cal_done to AH_FALSE; hopefully we'll find issues
  that creep up. It looks for something that doesn't run for
  scorpion, so we should be running calibrations for non-scorpion
  and then checking whether it succeeded/failed.