fireworks/bebob/oxfw: simplify a pattern of 'stream_running' and 'stream_stop'

In most case, the 'stream_stop' includes a condition of 'stream_running'.
This commit simply remove 'stream_running'.
fireworks/bebob/oxfw: keep consistency of substream counter

In ALSA's API design, PCM applications can execute 'hw_free' ioctl
several times. Then substream counter becomes inconsistent.

This commit is prevention from this situation.

Once 'hw_free' ioctl is executed, PCM runtime state becomes
'SNDRV_PCM_STATE_OPEN'. This is after hw_free() is executed in
each driver. So each driver can distinguish the process is first
time or not to refer to this state.