ALSA: firewire-lib: use IT context header to compute cycle count for scheduling packet

In IT context, header includes information of cycle to have processed
queued packet.

This commit uses the per-packet information to compute the cycle for
packet to be queued, instead of callback argument. In current
implementaion of ALSA IEC 61883-1/6 packet streaming engine, 48 packets
are queued at first to skip recent cycle. When IT context calls handler,
cycle information in header plus 48 cycle means the cycle to be going
to queue packet.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>