Bugfix: gridseed: use a signed integer so that returning -1 has defined behavior
Merge pull request #461 from nwoolls/bug/gridseed_firmware_neg1

Bugfix: gridseed: use a signed int so returning -1 has defined behavior
gridseed: added support for the 80-chip (two blades of 40 chips) G-Blade Scrypt-only miner