fs_mgr: fs_mgr_update_verity_state take std::function

By changing to a std:function from a plain function pointer as an
argument to fs_mgr_update_verity_state(), a lambda with captured
objects can be executed providing thread safety.

Test: compile and boot
Bug: 109821005
Change-Id: I2699a08cc2c5216625dcbf84eeac0c460f4ae36a