ALSA: firewire-lib: use variable size of queue for isoc packets instead of fixed...

ALSA: firewire-lib: use variable size of queue for isoc packets instead of fixed size

The number of packets in packet buffer has been fixed number (=48) since
first commit of ALSA IEC 61883-1/6 packet streaming engine.

This commit allows the engine to use variable number of packets in the
buffer. The size is calculated by a parameter in AMDTP domain structure
surely to store the number of events in the packets of buffer. Although
the value of parameter is expected to come from 'period size' parameter
of PCM substream, at present 48 is still used.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20191017155424.885-2-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Iwai <tiwai@suse.de>