Add management for both PCM and MIDI streams

According to IEC 61883-6, MIDI stream is multiplexed with PCM stream in an
Firewire isochronous stream. Then this module use the rules below:
[MIDI stream side]
 1.When no stream in both direction is started, start stream with 48000
 2.When stream in opposite direction is started, start stream with the same
   sampling rate.
 3.When stream in the same direction has PCM stream and request to stop MIDI
   stream, don't stop stream itself.
[PCM stream side]
 1.When stream in the both direction is started and has no PCM stream, stop
   the stream because it include just MIDI stream. Then restart it with
   requested sampling rate by PCM component.

 It's a bit complicated but needed for management for both streams.