fixed signed/unsigned warnings in fpga.cpp
fixed signed/unsigned warnings in fpga.cpp

RoboJackets/robocup-software,RoboJackets/robocup-software,JNeiger/robocup-software,RoboJackets/robocup-software,RoboJackets/robocup-software,JNeiger/robocup-software,JNeiger/robocup-software,JNeiger/robocup-software,JNeiger/robocup-software