ALSA: firewire-lib: pass no syt information to data block processing layer

In a previous commit, the variable passed from packet streaming layer
for syt variable is useless. This commit obsoletes it.

In my future work, the syt information is passed to data block processing
layer by another way.

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