ALSA: firewire-lib: fix return value on fail in amdtp_tscm_init()

If amdtp_stream_init() fails in amdtp_tscm_init(), the latter returns zero,
though it's supposed to return error code, which is checked inside
init_stream() in file tascam-stream.c.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 47faeea2 ("ALSA: firewire-tascam: add data block processing layer")
Signed-off-by: Murad Masimov <m.masimov@maxima.ru>
Reviewed-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20241101185517.1819-1-m.masimov@maxima.ru