ALSA: firewire-lib: code refactoring to queueing packets

This commit is a preparation to queue IT packet with header. To enable
packet handler to fill the header, this commit uses kernel stack for
data structure of packet parameter in several part of this file.

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