Allow controlling the delay for iris clocking
requested to merge fs-flash/embedded/raspberrypi/rpiris-server:feature/allow-delay-config into master
We notice that some iris'es do not open/close as one would expect. As it turns out, this can be fixed by increasing the delay times. But by now we do not run test-series to determine the best value, so we make it configurable and adjust the delay if necessary.
And since we can not store the values on the device, we have to do it from outside.