crypto: investigate if we can get rid of pearldiver status lock

[thibault-martinez]

[semenov-vladyslav]

Pearl diver's status can only be asynchronously assigned value of SEARCH_FINISHED. So even if two threads change status value it's always going to be SEARCH_FINISHED.

The lock might be needed if pearl diver supported interruption logic. In this case the access to status variable must be exclusive.