Add max reg read failures

Few chips with a bad connection might need to rensend data multiple times for each individual register read. While these chips might not pass a total of 10 read failures per register, the retries add up over multiple registers slowing down each scan significantly. Functionallity was added to define a maximal number of read failures for each chip. This value is specified in the testbench. If, during a scan, this max total is succeded, a exception is thrown.