ALSA: fireworks/bebob: Shorten critical section for stream_stop_duplex()

All assignment for local variables in these functions are not related to
critical section.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/firewire/fireworks/fireworks_stream.c b/sound/firewire/fireworks/fireworks_stream.c
index 5415690..b985fc5 100644
--- a/sound/firewire/fireworks/fireworks_stream.c
+++ b/sound/firewire/fireworks/fireworks_stream.c
@@ -284,8 +284,6 @@
 	struct amdtp_stream *master, *slave;
 	atomic_t *master_substreams, *slave_substreams;
 
-	mutex_lock(&efw->mutex);
-
 	if (efw->master == &efw->rx_stream) {
 		slave  = &efw->tx_stream;
 		master = &efw->rx_stream;
@@ -298,6 +296,8 @@
 		master_substreams = &efw->capture_substreams;
 	}
 
+	mutex_lock(&efw->mutex);
+
 	if (atomic_read(slave_substreams) == 0) {
 		stop_stream(efw, slave);