ALSA: firewire-lib: remove reference counting

AMDTP helper functions increment/decrement reference counter for an
instance of FireWire unit, while it's complicated for each driver to
process error state.

In previous commit, each driver has the role of reference counting. This
commit removes this role from the helper function.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Cc: <stable@vger.kernel.org> # 3.19+
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/firewire/amdtp.c

@@ -78,7 +78,7 @@ static void pcm_period_tasklet(unsigned long data);
 int amdtp_stream_init(struct amdtp_stream *s, struct fw_unit *unit,
 		      enum amdtp_stream_direction dir, enum cip_flags flags)
 {
-	s->unit = fw_unit_get(unit);
+	s->unit = unit;
 	s->direction = dir;
 	s->flags = flags;
 	s->context = ERR_PTR(-1);
@@ -102,7 +102,6 @@ void amdtp_stream_destroy(struct amdtp_stream *s)
 {
 	WARN_ON(amdtp_stream_running(s));
 	mutex_destroy(&s->mutex);
-	fw_unit_put(s->unit);
 }
 EXPORT_SYMBOL(amdtp_stream_destroy);