ALSA: firewire-tascam: Fix to handle error from initialization of stream data

This module has a bug not to return error code in a case that data
structure for transmitted packets fails to be initialized.

This commit fixes the bug.

Fixes: 35efa5c4

 ("ALSA: firewire-tascam: add streaming functionality")
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>