Add APIs for ENC624J600 cryptography engine

[rhalkyard]

The ENC624J600 has a hardware cryptography engine that can do modular exponentiation, and calculate MD5 and SHA1 digests (the datasheet also says it does AES, but the errata indicates this is buggy and should not be used).

There seems to be some interest in adding support for modern TLS to the classic Mac OS, and even a working implementation, but it sounds as though offload is the only practical way this could be achieved on 68k machines.

Additional Control calls could be added to the driver to expose this functionality to applications.