gridseed: Added support for Scrypt hashing with 5-chip GridSeed devices

AFAIK SHA-2 support *should* work for the GridSeed devices, but doesn't. Given resources and timing I've flagged the driver Scrypt-only for now. Adjusting the flag for SHA would allow anyone else to continue work on SHA support. Running with --device-protocol-dump generates protocol logs that are seemingly identical to working logs.