Here's a quick fix for alsa_in and alsa_out, which currently set the
playback latency of their ports to the target delay, but forget to
convert this delay to JACK frames. See PR for more info.
Also convert the result of jack_frames_since_cycle_start() into ALSA
frames, before subtracting it from the delay for the controller.
Note that this change only has effect if ALSA and JACK sample rates
differ, otherwise the behavior stays the same.